ksmutils: Add ksminfo utility

Add the ksminfo utility that prints information about the KSM pages
of a process

Change-Id: Ib6f5291cc28d57ef05adc861e71860aa83b56465

5 files changed, 1574 insertions, 0 deletions

diff --git a/ksmutils/Android.mk b/ksmutils/Android.mk
new file mode 100644
index 00000000..f34576d9
--- /dev/null
+++ b/ksmutils/Android.mk
@@ -0,0 +1,30 @@
+# Copyright (C) 2013 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+LOCAL_PATH:= $(call my-dir)
+include $(CLEAR_VARS)
+
+LOCAL_SRC_FILES := ksminfo.c lookup3.c
+
+LOCAL_C_INCLUDES := $(call include-path-for, libpagemap)
+
+LOCAL_SHARED_LIBRARIES := libpagemap
+
+LOCAL_MODULE := ksminfo
+
+LOCAL_MODULE_PATH := $(TARGET_OUT_OPTIONAL_EXECUTABLES)
+
+LOCAL_MODULE_TAGS := debug
+
+include $(BUILD_EXECUTABLE)
diff --git a/ksmutils/MODULE_LICENSE_APACHE2 b/ksmutils/MODULE_LICENSE_APACHE2
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/ksmutils/MODULE_LICENSE_APACHE2
diff --git a/ksmutils/NOTICE b/ksmutils/NOTICE
new file mode 100644
index 00000000..c5b1efa7
--- /dev/null
+++ b/ksmutils/NOTICE
@@ -0,0 +1,190 @@
+
+   Copyright (c) 2005-2008, The Android Open Source Project
+
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+
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+
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diff --git a/ksmutils/ksminfo.c b/ksmutils/ksminfo.c
new file mode 100644
index 00000000..9423f4ff
--- /dev/null
+++ b/ksmutils/ksminfo.c
@@ -0,0 +1,352 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <errno.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <string.h>
+#include <fcntl.h>
+#include <stdint.h>
+#include <getopt.h>
+
+#include <pagemap/pagemap.h>
+
+#define MAX_FILENAME  64
+
+#define GROWTH_FACTOR 10
+
+#define NO_PATTERN    0x100
+
+static void usage(char *myname);
+static int getprocname(pid_t pid, char *buf, int len);
+static void print_ksm_pages(pm_map_t **maps, size_t num_maps, bool verbose);
+static bool is_pattern(uint8_t *data, size_t len);
+extern uint32_t hashword(const uint32_t *, size_t, int32_t);
+
+struct ksm_page {
+    uint32_t hash;
+    unsigned long *vaddr;
+    size_t vaddr_len, vaddr_size;
+    uint16_t pattern;
+};
+
+int main(int argc, char *argv[]) {
+    pm_kernel_t *ker;
+    pm_process_t *proc;
+    pid_t pid;
+    pm_map_t **maps;
+    size_t num_maps;
+    char cmdline[256]; // this must be within the range of int
+    int error;
+    int rc = EXIT_SUCCESS;
+    bool verbose = false;
+
+    opterr = 0;
+    do {
+        int c = getopt(argc, argv, "hv");
+        if (c == -1)
+            break;
+
+        switch (c) {
+            case 'v':
+                verbose = true;
+                break;
+            case 'h':
+                usage(argv[0]);
+                exit(EXIT_SUCCESS);
+            case '?':
+                fprintf(stderr, "unknown option: %c\n", optopt);
+                usage(argv[0]);
+                exit(EXIT_FAILURE);
+        }
+    } while (1);
+
+    if (optind != argc - 1) {
+        usage(argv[0]);
+        exit(EXIT_FAILURE);
+    }
+
+    pid = strtoul(argv[optind], NULL, 10);
+    if (pid == 0) {
+        fprintf(stderr, "Invalid PID\n");
+        exit(EXIT_FAILURE);
+    }
+
+    error = pm_kernel_create(&ker);
+    if (error) {
+        fprintf(stderr, "Error creating kernel interface -- "
+                        "does this kernel have pagemap?\n");
+        exit(EXIT_FAILURE);
+    }
+
+    error = pm_process_create(ker, pid, &proc);
+    if (error) {
+        fprintf(stderr, "warning: could not create process interface for %d\n", pid);
+        exit(EXIT_FAILURE);
+    }
+
+    error = pm_process_maps(proc, &maps, &num_maps);
+    if (error) {
+        fprintf(stderr, "warning: could not read process map for %d\n", pid);
+        rc = EXIT_FAILURE;
+        goto destroy_proc;
+    }
+
+    if (getprocname(pid, cmdline, sizeof(cmdline)) < 0) {
+        cmdline[0] = '\0';
+    }
+    printf("%s (%u):\n", cmdline, pid);
+    printf("Warning: this tool only compares the KSM CRCs of pages, there is a chance of "
+            "collisions\n");
+    print_ksm_pages(maps, num_maps, verbose);
+
+    free(maps);
+destroy_proc:
+    pm_process_destroy(proc);
+    return rc;
+}
+
+static void print_ksm_pages(pm_map_t **maps, size_t num_maps, bool verbose) {
+    size_t i, j, k;
+    size_t len;
+    uint64_t *pagemap;
+    size_t map_len;
+    uint64_t flags;
+    pm_kernel_t *ker;
+    int error;
+    unsigned long vaddr;
+    int fd;
+    off_t off;
+    char filename[MAX_FILENAME];
+    uint32_t *data;
+    uint32_t hash;
+    struct ksm_page *pages;
+    size_t pages_len, pages_size;
+
+    if (num_maps <= 0)
+        return;
+
+    ker = maps[0]->proc->ker;
+    error = snprintf(filename, MAX_FILENAME, "/proc/%d/mem", pm_process_pid(maps[0]->proc));
+    if (error < 0 || error >= MAX_FILENAME) {
+        return;
+    }
+
+    data = malloc(pm_kernel_pagesize(ker));
+    if (data == NULL) {
+        fprintf(stderr, "warning: not enough memory to malloc data buffer\n");
+        return;
+    }
+
+    fd = open(filename, O_RDONLY);
+    if (fd < 0) {
+        fprintf(stderr, "warning: could not open %s\n", filename);
+        goto err_open;
+    }
+
+    pages = NULL;
+    pages_size = 0;
+    pages_len = 0;
+
+    for (i = 0; i < num_maps; i++) {
+        error = pm_map_pagemap(maps[i], &pagemap, &map_len);
+        if (error) {
+            fprintf(stderr, "warning: could not read the pagemap of %d\n",
+                    pm_process_pid(maps[i]->proc));
+        }
+        for (j = 0; j < map_len; j++) {
+            error = pm_kernel_flags(ker, pagemap[j], &flags);
+            if (error) {
+                fprintf(stderr, "warning: could not read flags for pfn at address 0x%016llx\n",
+                        pagemap[i]);
+                continue;
+            }
+            if (!(flags & PM_PAGE_KSM)) {
+                continue;
+            }
+            vaddr = pm_map_start(maps[i]) + j * pm_kernel_pagesize(ker);
+            off = lseek(fd, vaddr, SEEK_SET);
+            if (off == (off_t)-1) {
+                fprintf(stderr, "warning: could not lseek to 0x%08lx\n", vaddr);
+                continue;
+            }
+            len = read(fd, data, pm_kernel_pagesize(ker));
+            if (len != pm_kernel_pagesize(ker)) {
+                fprintf(stderr, "warning: could not read page at 0x%08lx\n", vaddr);
+                continue;
+            }
+
+            hash = hashword(data, pm_kernel_pagesize(ker) / sizeof(*data), 17);
+
+            for (k = 0; k < pages_len; k++) {
+                if (pages[k].hash == hash) break;
+            }
+
+            if (k == pages_len) {
+                if (pages_len == pages_size) {
+                    struct ksm_page *tmp = realloc(pages,
+                            (pages_size + GROWTH_FACTOR) * sizeof(*pages));
+                    if (tmp == NULL) {
+                        fprintf(stderr, "warning: not enough memory to realloc pages struct\n");
+                        free(pagemap);
+                        goto err_realloc;
+                    }
+                    memset(&tmp[k], 0, sizeof(tmp[k]) * GROWTH_FACTOR);
+                    pages = tmp;
+                    pages_size += GROWTH_FACTOR;
+                }
+                pages[pages_len].hash = hash;
+                pages[pages_len].pattern = is_pattern((uint8_t *)data, pm_kernel_pagesize(ker)) ?
+                        (data[0] & 0xFF) : NO_PATTERN;
+                pages_len++;
+            }
+
+            if (verbose) {
+                if (pages[k].vaddr_len == pages[k].vaddr_size) {
+                    unsigned long *tmp = realloc(pages[k].vaddr,
+                            (pages[k].vaddr_size + GROWTH_FACTOR) * sizeof(*(pages[k].vaddr)));
+                    if (tmp == NULL) {
+                        fprintf(stderr, "warning: not enough memory to realloc vaddr array\n");
+                        free(pagemap);
+                        goto err_realloc;
+                    }
+                    memset(&tmp[pages[k].vaddr_len], 0, sizeof(tmp[pages[k].vaddr_len]) * GROWTH_FACTOR);
+                    pages[k].vaddr = tmp;
+                    pages[k].vaddr_size += GROWTH_FACTOR;
+                }
+                pages[k].vaddr[pages[k].vaddr_len] = vaddr;
+            }
+            pages[k].vaddr_len++;
+        }
+        free(pagemap);
+    }
+
+    for (i = 0; i < pages_len; i++) {
+        if (pages[i].pattern != NO_PATTERN) {
+            printf("0x%02x byte pattern: ", pages[i].pattern);
+        } else {
+            printf("KSM CRC 0x%08x:", pages[i].hash);
+        }
+        printf(" %4d page", pages[i].vaddr_len);
+        if (pages[i].vaddr_len > 1) {
+            printf("s");
+        }
+        printf("\n");
+
+        if (verbose) {
+            j = 0;
+            while (j < pages[i].vaddr_len) {
+                printf("                   ");
+                for (k = 0; k < 8 && j < pages[i].vaddr_len; k++, j++) {
+                    printf(" 0x%08lx", pages[i].vaddr[j]);
+                }
+                printf("\n");
+            }
+        }
+    }
+
+err_realloc:
+    if (verbose) {
+        for (i = 0; i < pages_len; i++) {
+            free(pages[i].vaddr);
+        }
+    }
+    free(pages);
+err_pages:
+    close(fd);
+err_open:
+    free(data);
+}
+
+static void usage(char *myname) {
+    fprintf(stderr, "Usage: %s [ -v | -h ] <pid>\n"
+                    "    -v  Verbose: print virtual addresses.\n"
+                    "    -h  Display this help screen.\n",
+    myname);
+}
+
+static bool is_pattern(uint8_t *data, size_t len) {
+    size_t i;
+    uint8_t first_byte = data[0];
+
+    for (i = 1; i < len; i++) {
+        if (first_byte != data[i]) return false;
+    }
+
+    return true;
+}
+
+/*
+ * Get the process name for a given PID. Inserts the process name into buffer
+ * buf of length len. The size of the buffer must be greater than zero to get
+ * any useful output.
+ *
+ * Note that fgets(3) only declares length as an int, so our buffer size is
+ * also declared as an int.
+ *
+ * Returns 0 on success, a positive value on partial success, and -1 on
+ * failure. Other interesting values:
+ *   1 on failure to create string to examine proc cmdline entry
+ *   2 on failure to open proc cmdline entry
+ *   3 on failure to read proc cmdline entry
+ */
+static int getprocname(pid_t pid, char *buf, int len) {
+    char *filename;
+    FILE *f;
+    int rc = 0;
+    static const char* unknown_cmdline = "<unknown>";
+
+    if (len <= 0) {
+        return -1;
+    }
+
+    if (asprintf(&filename, "/proc/%zd/cmdline", pid) < 0) {
+        rc = 1;
+        goto exit;
+    }
+
+    f = fopen(filename, "r");
+    if (f == NULL) {
+        rc = 2;
+        goto releasefilename;
+    }
+
+    if (fgets(buf, len, f) == NULL) {
+        rc = 3;
+        goto closefile;
+    }
+
+closefile:
+    (void) fclose(f);
+releasefilename:
+    free(filename);
+exit:
+    if (rc != 0) {
+        /*
+         * The process went away before we could read its process name. Try
+         * to give the user "<unknown>" here, but otherwise they get to look
+         * at a blank.
+         */
+        if (strlcpy(buf, unknown_cmdline, (size_t)len) >= (size_t)len) {
+            rc = 4;
+        }
+    }
+
+    return rc;
+}
+
diff --git a/ksmutils/lookup3.c b/ksmutils/lookup3.c
new file mode 100644
index 00000000..e6072958
--- /dev/null
+++ b/ksmutils/lookup3.c
@@ -0,0 +1,1002 @@
+/*
+-------------------------------------------------------------------------------
+lookup3.c, by Bob Jenkins, May 2006, Public Domain.
+
+These are functions for producing 32-bit hashes for hash table lookup.
+hashword(), hashlittle(), hashlittle2(), hashbig(), mix(), and final() 
+are externally useful functions.  Routines to test the hash are included 
+if SELF_TEST is defined.  You can use this free for any purpose.  It's in
+the public domain.  It has no warranty.
+
+You probably want to use hashlittle().  hashlittle() and hashbig()
+hash byte arrays.  hashlittle() is is faster than hashbig() on
+little-endian machines.  Intel and AMD are little-endian machines.
+On second thought, you probably want hashlittle2(), which is identical to
+hashlittle() except it returns two 32-bit hashes for the price of one.  
+You could implement hashbig2() if you wanted but I haven't bothered here.
+
+If you want to find a hash of, say, exactly 7 integers, do
+  a = i1;  b = i2;  c = i3;
+  mix(a,b,c);
+  a += i4; b += i5; c += i6;
+  mix(a,b,c);
+  a += i7;
+  final(a,b,c);
+then use c as the hash value.  If you have a variable length array of
+4-byte integers to hash, use hashword().  If you have a byte array (like
+a character string), use hashlittle().  If you have several byte arrays, or
+a mix of things, see the comments above hashlittle().  
+
+Why is this so big?  I read 12 bytes at a time into 3 4-byte integers, 
+then mix those integers.  This is fast (you can do a lot more thorough
+mixing with 12*3 instructions on 3 integers than you can with 3 instructions
+on 1 byte), but shoehorning those bytes into integers efficiently is messy.
+-------------------------------------------------------------------------------
+*/
+#define SELF_TEST 1
+#undef SELF_TEST
+
+#include <stdio.h>      /* defines printf for tests */
+#include <time.h>       /* defines time_t for timings in the test */
+#include <stdint.h>     /* defines uint32_t etc */
+#include <sys/param.h>  /* attempt to define endianness */
+#ifdef linux
+# include <endian.h>    /* attempt to define endianness */
+#endif
+
+/*
+ * My best guess at if you are big-endian or little-endian.  This may
+ * need adjustment.
+ */
+#if (defined(__BYTE_ORDER) && defined(__LITTLE_ENDIAN) && \
+     __BYTE_ORDER == __LITTLE_ENDIAN) || \
+    (defined(i386) || defined(__i386__) || defined(__i486__) || \
+     defined(__i586__) || defined(__i686__) || defined(vax) || defined(MIPSEL))
+# define HASH_LITTLE_ENDIAN 1
+# define HASH_BIG_ENDIAN 0
+#elif (defined(__BYTE_ORDER) && defined(__BIG_ENDIAN) && \
+       __BYTE_ORDER == __BIG_ENDIAN) || \
+      (defined(sparc) || defined(POWERPC) || defined(mc68000) || defined(sel))
+# define HASH_LITTLE_ENDIAN 0
+# define HASH_BIG_ENDIAN 1
+#else
+# define HASH_LITTLE_ENDIAN 0
+# define HASH_BIG_ENDIAN 0
+#endif
+
+#define hashsize(n) ((uint32_t)1<<(n))
+#define hashmask(n) (hashsize(n)-1)
+#define rot(x,k) (((x)<<(k)) | ((x)>>(32-(k))))
+
+/*
+-------------------------------------------------------------------------------
+mix -- mix 3 32-bit values reversibly.
+
+This is reversible, so any information in (a,b,c) before mix() is
+still in (a,b,c) after mix().
+
+If four pairs of (a,b,c) inputs are run through mix(), or through
+mix() in reverse, there are at least 32 bits of the output that
+are sometimes the same for one pair and different for another pair.
+This was tested for:
+* pairs that differed by one bit, by two bits, in any combination
+  of top bits of (a,b,c), or in any combination of bottom bits of
+  (a,b,c).
+* "differ" is defined as +, -, ^, or ~^.  For + and -, I transformed
+  the output delta to a Gray code (a^(a>>1)) so a string of 1's (as
+  is commonly produced by subtraction) look like a single 1-bit
+  difference.
+* the base values were pseudorandom, all zero but one bit set, or 
+  all zero plus a counter that starts at zero.
+
+Some k values for my "a-=c; a^=rot(c,k); c+=b;" arrangement that
+satisfy this are
+    4  6  8 16 19  4
+    9 15  3 18 27 15
+   14  9  3  7 17  3
+Well, "9 15 3 18 27 15" didn't quite get 32 bits diffing
+for "differ" defined as + with a one-bit base and a two-bit delta.  I
+used http://burtleburtle.net/bob/hash/avalanche.html to choose 
+the operations, constants, and arrangements of the variables.
+
+This does not achieve avalanche.  There are input bits of (a,b,c)
+that fail to affect some output bits of (a,b,c), especially of a.  The
+most thoroughly mixed value is c, but it doesn't really even achieve
+avalanche in c.
+
+This allows some parallelism.  Read-after-writes are good at doubling
+the number of bits affected, so the goal of mixing pulls in the opposite
+direction as the goal of parallelism.  I did what I could.  Rotates
+seem to cost as much as shifts on every machine I could lay my hands
+on, and rotates are much kinder to the top and bottom bits, so I used
+rotates.
+-------------------------------------------------------------------------------
+*/
+#define mix(a,b,c) \
+{ \
+  a -= c;  a ^= rot(c, 4);  c += b; \
+  b -= a;  b ^= rot(a, 6);  a += c; \
+  c -= b;  c ^= rot(b, 8);  b += a; \
+  a -= c;  a ^= rot(c,16);  c += b; \
+  b -= a;  b ^= rot(a,19);  a += c; \
+  c -= b;  c ^= rot(b, 4);  b += a; \
+}
+
+/*
+-------------------------------------------------------------------------------
+final -- final mixing of 3 32-bit values (a,b,c) into c
+
+Pairs of (a,b,c) values differing in only a few bits will usually
+produce values of c that look totally different.  This was tested for
+* pairs that differed by one bit, by two bits, in any combination
+  of top bits of (a,b,c), or in any combination of bottom bits of
+  (a,b,c).
+* "differ" is defined as +, -, ^, or ~^.  For + and -, I transformed
+  the output delta to a Gray code (a^(a>>1)) so a string of 1's (as
+  is commonly produced by subtraction) look like a single 1-bit
+  difference.
+* the base values were pseudorandom, all zero but one bit set, or 
+  all zero plus a counter that starts at zero.
+
+These constants passed:
+ 14 11 25 16 4 14 24
+ 12 14 25 16 4 14 24
+and these came close:
+  4  8 15 26 3 22 24
+ 10  8 15 26 3 22 24
+ 11  8 15 26 3 22 24
+-------------------------------------------------------------------------------
+*/
+#define final(a,b,c) \
+{ \
+  c ^= b; c -= rot(b,14); \
+  a ^= c; a -= rot(c,11); \
+  b ^= a; b -= rot(a,25); \
+  c ^= b; c -= rot(b,16); \
+  a ^= c; a -= rot(c,4);  \
+  b ^= a; b -= rot(a,14); \
+  c ^= b; c -= rot(b,24); \
+}
+
+/*
+--------------------------------------------------------------------
+ This works on all machines.  To be useful, it requires
+ -- that the key be an array of uint32_t's, and
+ -- that the length be the number of uint32_t's in the key
+
+ The function hashword() is identical to hashlittle() on little-endian
+ machines, and identical to hashbig() on big-endian machines,
+ except that the length has to be measured in uint32_ts rather than in
+ bytes.  hashlittle() is more complicated than hashword() only because
+ hashlittle() has to dance around fitting the key bytes into registers.
+--------------------------------------------------------------------
+*/
+uint32_t hashword(
+const uint32_t *k,                   /* the key, an array of uint32_t values */
+size_t          length,               /* the length of the key, in uint32_ts */
+uint32_t        initval)         /* the previous hash, or an arbitrary value */
+{
+  uint32_t a,b,c;
+
+  /* Set up the internal state */
+  a = b = c = 0xdeadbeef + (((uint32_t)length)<<2) + initval;
+
+  /*------------------------------------------------- handle most of the key */
+  while (length > 3)
+  {
+    a += k[0];
+    b += k[1];
+    c += k[2];
+    mix(a,b,c);
+    length -= 3;
+    k += 3;
+  }
+
+  /*------------------------------------------- handle the last 3 uint32_t's */
+  switch(length)                     /* all the case statements fall through */
+  { 
+  case 3 : c+=k[2];
+  case 2 : b+=k[1];
+  case 1 : a+=k[0];
+    final(a,b,c);
+  case 0:     /* case 0: nothing left to add */
+    break;
+  }
+  /*------------------------------------------------------ report the result */
+  return c;
+}
+
+
+/*
+--------------------------------------------------------------------
+hashword2() -- same as hashword(), but take two seeds and return two
+32-bit values.  pc and pb must both be nonnull, and *pc and *pb must
+both be initialized with seeds.  If you pass in (*pb)==0, the output 
+(*pc) will be the same as the return value from hashword().
+--------------------------------------------------------------------
+*/
+void hashword2 (
+const uint32_t *k,                   /* the key, an array of uint32_t values */
+size_t          length,               /* the length of the key, in uint32_ts */
+uint32_t       *pc,                      /* IN: seed OUT: primary hash value */
+uint32_t       *pb)               /* IN: more seed OUT: secondary hash value */
+{
+  uint32_t a,b,c;
+
+  /* Set up the internal state */
+  a = b = c = 0xdeadbeef + ((uint32_t)(length<<2)) + *pc;
+  c += *pb;
+
+  /*------------------------------------------------- handle most of the key */
+  while (length > 3)
+  {
+    a += k[0];
+    b += k[1];
+    c += k[2];
+    mix(a,b,c);
+    length -= 3;
+    k += 3;
+  }
+
+  /*------------------------------------------- handle the last 3 uint32_t's */
+  switch(length)                     /* all the case statements fall through */
+  { 
+  case 3 : c+=k[2];
+  case 2 : b+=k[1];
+  case 1 : a+=k[0];
+    final(a,b,c);
+  case 0:     /* case 0: nothing left to add */
+    break;
+  }
+  /*------------------------------------------------------ report the result */
+  *pc=c; *pb=b;
+}
+
+
+/*
+-------------------------------------------------------------------------------
+hashlittle() -- hash a variable-length key into a 32-bit value
+  k       : the key (the unaligned variable-length array of bytes)
+  length  : the length of the key, counting by bytes
+  initval : can be any 4-byte value
+Returns a 32-bit value.  Every bit of the key affects every bit of
+the return value.  Two keys differing by one or two bits will have
+totally different hash values.
+
+The best hash table sizes are powers of 2.  There is no need to do
+mod a prime (mod is sooo slow!).  If you need less than 32 bits,
+use a bitmask.  For example, if you need only 10 bits, do
+  h = (h & hashmask(10));
+In which case, the hash table should have hashsize(10) elements.
+
+If you are hashing n strings (uint8_t **)k, do it like this:
+  for (i=0, h=0; i<n; ++i) h = hashlittle( k[i], len[i], h);
+
+By Bob Jenkins, 2006.  bob_jenkins@burtleburtle.net.  You may use this
+code any way you wish, private, educational, or commercial.  It's free.
+
+Use for hash table lookup, or anything where one collision in 2^^32 is
+acceptable.  Do NOT use for cryptographic purposes.
+-------------------------------------------------------------------------------
+*/
+
+uint32_t hashlittle( const void *key, size_t length, uint32_t initval)
+{
+  uint32_t a,b,c;                                          /* internal state */
+  union { const void *ptr; size_t i; } u;     /* needed for Mac Powerbook G4 */
+
+  /* Set up the internal state */
+  a = b = c = 0xdeadbeef + ((uint32_t)length) + initval;
+
+  u.ptr = key;
+  if (HASH_LITTLE_ENDIAN && ((u.i & 0x3) == 0)) {
+    const uint32_t *k = (const uint32_t *)key;         /* read 32-bit chunks */
+    const uint8_t  *k8;
+
+    /*------ all but last block: aligned reads and affect 32 bits of (a,b,c) */
+    while (length > 12)
+    {
+      a += k[0];
+      b += k[1];
+      c += k[2];
+      mix(a,b,c);
+      length -= 12;
+      k += 3;
+    }
+
+    /*----------------------------- handle the last (probably partial) block */
+    /* 
+     * "k[2]&0xffffff" actually reads beyond the end of the string, but
+     * then masks off the part it's not allowed to read.  Because the
+     * string is aligned, the masked-off tail is in the same word as the
+     * rest of the string.  Every machine with memory protection I've seen
+     * does it on word boundaries, so is OK with this.  But VALGRIND will
+     * still catch it and complain.  The masking trick does make the hash
+     * noticably faster for short strings (like English words).
+     */
+#ifndef VALGRIND
+
+    switch(length)
+    {
+    case 12: c+=k[2]; b+=k[1]; a+=k[0]; break;
+    case 11: c+=k[2]&0xffffff; b+=k[1]; a+=k[0]; break;
+    case 10: c+=k[2]&0xffff; b+=k[1]; a+=k[0]; break;
+    case 9 : c+=k[2]&0xff; b+=k[1]; a+=k[0]; break;
+    case 8 : b+=k[1]; a+=k[0]; break;
+    case 7 : b+=k[1]&0xffffff; a+=k[0]; break;
+    case 6 : b+=k[1]&0xffff; a+=k[0]; break;
+    case 5 : b+=k[1]&0xff; a+=k[0]; break;
+    case 4 : a+=k[0]; break;
+    case 3 : a+=k[0]&0xffffff; break;
+    case 2 : a+=k[0]&0xffff; break;
+    case 1 : a+=k[0]&0xff; break;
+    case 0 : return c;              /* zero length strings require no mixing */
+    }
+
+#else /* make valgrind happy */
+
+    k8 = (const uint8_t *)k;
+    switch(length)
+    {
+    case 12: c+=k[2]; b+=k[1]; a+=k[0]; break;
+    case 11: c+=((uint32_t)k8[10])<<16;  /* fall through */
+    case 10: c+=((uint32_t)k8[9])<<8;    /* fall through */
+    case 9 : c+=k8[8];                   /* fall through */
+    case 8 : b+=k[1]; a+=k[0]; break;
+    case 7 : b+=((uint32_t)k8[6])<<16;   /* fall through */
+    case 6 : b+=((uint32_t)k8[5])<<8;    /* fall through */
+    case 5 : b+=k8[4];                   /* fall through */
+    case 4 : a+=k[0]; break;
+    case 3 : a+=((uint32_t)k8[2])<<16;   /* fall through */
+    case 2 : a+=((uint32_t)k8[1])<<8;    /* fall through */
+    case 1 : a+=k8[0]; break;
+    case 0 : return c;
+    }
+
+#endif /* !valgrind */
+
+  } else if (HASH_LITTLE_ENDIAN && ((u.i & 0x1) == 0)) {
+    const uint16_t *k = (const uint16_t *)key;         /* read 16-bit chunks */
+    const uint8_t  *k8;
+
+    /*--------------- all but last block: aligned reads and different mixing */
+    while (length > 12)
+    {
+      a += k[0] + (((uint32_t)k[1])<<16);
+      b += k[2] + (((uint32_t)k[3])<<16);
+      c += k[4] + (((uint32_t)k[5])<<16);
+      mix(a,b,c);
+      length -= 12;
+      k += 6;
+    }
+
+    /*----------------------------- handle the last (probably partial) block */
+    k8 = (const uint8_t *)k;
+    switch(length)
+    {
+    case 12: c+=k[4]+(((uint32_t)k[5])<<16);
+             b+=k[2]+(((uint32_t)k[3])<<16);
+             a+=k[0]+(((uint32_t)k[1])<<16);
+             break;
+    case 11: c+=((uint32_t)k8[10])<<16;     /* fall through */
+    case 10: c+=k[4];
+             b+=k[2]+(((uint32_t)k[3])<<16);
+             a+=k[0]+(((uint32_t)k[1])<<16);
+             break;
+    case 9 : c+=k8[8];                      /* fall through */
+    case 8 : b+=k[2]+(((uint32_t)k[3])<<16);
+             a+=k[0]+(((uint32_t)k[1])<<16);
+             break;
+    case 7 : b+=((uint32_t)k8[6])<<16;      /* fall through */
+    case 6 : b+=k[2];
+             a+=k[0]+(((uint32_t)k[1])<<16);
+             break;
+    case 5 : b+=k8[4];                      /* fall through */
+    case 4 : a+=k[0]+(((uint32_t)k[1])<<16);
+             break;
+    case 3 : a+=((uint32_t)k8[2])<<16;      /* fall through */
+    case 2 : a+=k[0];
+             break;
+    case 1 : a+=k8[0];
+             break;
+    case 0 : return c;                     /* zero length requires no mixing */
+    }
+
+  } else {                        /* need to read the key one byte at a time */
+    const uint8_t *k = (const uint8_t *)key;
+
+    /*--------------- all but the last block: affect some 32 bits of (a,b,c) */
+    while (length > 12)
+    {
+      a += k[0];
+      a += ((uint32_t)k[1])<<8;
+      a += ((uint32_t)k[2])<<16;
+      a += ((uint32_t)k[3])<<24;
+      b += k[4];
+      b += ((uint32_t)k[5])<<8;
+      b += ((uint32_t)k[6])<<16;
+      b += ((uint32_t)k[7])<<24;
+      c += k[8];
+      c += ((uint32_t)k[9])<<8;
+      c += ((uint32_t)k[10])<<16;
+      c += ((uint32_t)k[11])<<24;
+      mix(a,b,c);
+      length -= 12;
+      k += 12;
+    }
+
+    /*-------------------------------- last block: affect all 32 bits of (c) */
+    switch(length)                   /* all the case statements fall through */
+    {
+    case 12: c+=((uint32_t)k[11])<<24;
+    case 11: c+=((uint32_t)k[10])<<16;
+    case 10: c+=((uint32_t)k[9])<<8;
+    case 9 : c+=k[8];
+    case 8 : b+=((uint32_t)k[7])<<24;
+    case 7 : b+=((uint32_t)k[6])<<16;
+    case 6 : b+=((uint32_t)k[5])<<8;
+    case 5 : b+=k[4];
+    case 4 : a+=((uint32_t)k[3])<<24;
+    case 3 : a+=((uint32_t)k[2])<<16;
+    case 2 : a+=((uint32_t)k[1])<<8;
+    case 1 : a+=k[0];
+             break;
+    case 0 : return c;
+    }
+  }
+
+  final(a,b,c);
+  return c;
+}
+
+
+/*
+ * hashlittle2: return 2 32-bit hash values
+ *
+ * This is identical to hashlittle(), except it returns two 32-bit hash
+ * values instead of just one.  This is good enough for hash table
+ * lookup with 2^^64 buckets, or if you want a second hash if you're not
+ * happy with the first, or if you want a probably-unique 64-bit ID for
+ * the key.  *pc is better mixed than *pb, so use *pc first.  If you want
+ * a 64-bit value do something like "*pc + (((uint64_t)*pb)<<32)".
+ */
+void hashlittle2( 
+  const void *key,       /* the key to hash */
+  size_t      length,    /* length of the key */
+  uint32_t   *pc,        /* IN: primary initval, OUT: primary hash */
+  uint32_t   *pb)        /* IN: secondary initval, OUT: secondary hash */
+{
+  uint32_t a,b,c;                                          /* internal state */
+  union { const void *ptr; size_t i; } u;     /* needed for Mac Powerbook G4 */
+
+  /* Set up the internal state */
+  a = b = c = 0xdeadbeef + ((uint32_t)length) + *pc;
+  c += *pb;
+
+  u.ptr = key;
+  if (HASH_LITTLE_ENDIAN && ((u.i & 0x3) == 0)) {
+    const uint32_t *k = (const uint32_t *)key;         /* read 32-bit chunks */
+    const uint8_t  *k8;
+
+    /*------ all but last block: aligned reads and affect 32 bits of (a,b,c) */
+    while (length > 12)
+    {
+      a += k[0];
+      b += k[1];
+      c += k[2];
+      mix(a,b,c);
+      length -= 12;
+      k += 3;
+    }
+
+    /*----------------------------- handle the last (probably partial) block */
+    /* 
+     * "k[2]&0xffffff" actually reads beyond the end of the string, but
+     * then masks off the part it's not allowed to read.  Because the
+     * string is aligned, the masked-off tail is in the same word as the
+     * rest of the string.  Every machine with memory protection I've seen
+     * does it on word boundaries, so is OK with this.  But VALGRIND will
+     * still catch it and complain.  The masking trick does make the hash
+     * noticably faster for short strings (like English words).
+     */
+#ifndef VALGRIND
+
+    switch(length)
+    {
+    case 12: c+=k[2]; b+=k[1]; a+=k[0]; break;
+    case 11: c+=k[2]&0xffffff; b+=k[1]; a+=k[0]; break;
+    case 10: c+=k[2]&0xffff; b+=k[1]; a+=k[0]; break;
+    case 9 : c+=k[2]&0xff; b+=k[1]; a+=k[0]; break;
+    case 8 : b+=k[1]; a+=k[0]; break;
+    case 7 : b+=k[1]&0xffffff; a+=k[0]; break;
+    case 6 : b+=k[1]&0xffff; a+=k[0]; break;
+    case 5 : b+=k[1]&0xff; a+=k[0]; break;
+    case 4 : a+=k[0]; break;
+    case 3 : a+=k[0]&0xffffff; break;
+    case 2 : a+=k[0]&0xffff; break;
+    case 1 : a+=k[0]&0xff; break;
+    case 0 : *pc=c; *pb=b; return;  /* zero length strings require no mixing */
+    }
+
+#else /* make valgrind happy */
+
+    k8 = (const uint8_t *)k;
+    switch(length)
+    {
+    case 12: c+=k[2]; b+=k[1]; a+=k[0]; break;
+    case 11: c+=((uint32_t)k8[10])<<16;  /* fall through */
+    case 10: c+=((uint32_t)k8[9])<<8;    /* fall through */
+    case 9 : c+=k8[8];                   /* fall through */
+    case 8 : b+=k[1]; a+=k[0]; break;
+    case 7 : b+=((uint32_t)k8[6])<<16;   /* fall through */
+    case 6 : b+=((uint32_t)k8[5])<<8;    /* fall through */
+    case 5 : b+=k8[4];                   /* fall through */
+    case 4 : a+=k[0]; break;
+    case 3 : a+=((uint32_t)k8[2])<<16;   /* fall through */
+    case 2 : a+=((uint32_t)k8[1])<<8;    /* fall through */
+    case 1 : a+=k8[0]; break;
+    case 0 : *pc=c; *pb=b; return;  /* zero length strings require no mixing */
+    }
+
+#endif /* !valgrind */
+
+  } else if (HASH_LITTLE_ENDIAN && ((u.i & 0x1) == 0)) {
+    const uint16_t *k = (const uint16_t *)key;         /* read 16-bit chunks */
+    const uint8_t  *k8;
+
+    /*--------------- all but last block: aligned reads and different mixing */
+    while (length > 12)
+    {
+      a += k[0] + (((uint32_t)k[1])<<16);
+      b += k[2] + (((uint32_t)k[3])<<16);
+      c += k[4] + (((uint32_t)k[5])<<16);
+      mix(a,b,c);
+      length -= 12;
+      k += 6;
+    }
+
+    /*----------------------------- handle the last (probably partial) block */
+    k8 = (const uint8_t *)k;
+    switch(length)
+    {
+    case 12: c+=k[4]+(((uint32_t)k[5])<<16);
+             b+=k[2]+(((uint32_t)k[3])<<16);
+             a+=k[0]+(((uint32_t)k[1])<<16);
+             break;
+    case 11: c+=((uint32_t)k8[10])<<16;     /* fall through */
+    case 10: c+=k[4];
+             b+=k[2]+(((uint32_t)k[3])<<16);
+             a+=k[0]+(((uint32_t)k[1])<<16);
+             break;
+    case 9 : c+=k8[8];                      /* fall through */
+    case 8 : b+=k[2]+(((uint32_t)k[3])<<16);
+             a+=k[0]+(((uint32_t)k[1])<<16);
+             break;
+    case 7 : b+=((uint32_t)k8[6])<<16;      /* fall through */
+    case 6 : b+=k[2];
+             a+=k[0]+(((uint32_t)k[1])<<16);
+             break;
+    case 5 : b+=k8[4];                      /* fall through */
+    case 4 : a+=k[0]+(((uint32_t)k[1])<<16);
+             break;
+    case 3 : a+=((uint32_t)k8[2])<<16;      /* fall through */
+    case 2 : a+=k[0];
+             break;
+    case 1 : a+=k8[0];
+             break;
+    case 0 : *pc=c; *pb=b; return;  /* zero length strings require no mixing */
+    }
+
+  } else {                        /* need to read the key one byte at a time */
+    const uint8_t *k = (const uint8_t *)key;
+
+    /*--------------- all but the last block: affect some 32 bits of (a,b,c) */
+    while (length > 12)
+    {
+      a += k[0];
+      a += ((uint32_t)k[1])<<8;
+      a += ((uint32_t)k[2])<<16;
+      a += ((uint32_t)k[3])<<24;
+      b += k[4];
+      b += ((uint32_t)k[5])<<8;
+      b += ((uint32_t)k[6])<<16;
+      b += ((uint32_t)k[7])<<24;
+      c += k[8];
+      c += ((uint32_t)k[9])<<8;
+      c += ((uint32_t)k[10])<<16;
+      c += ((uint32_t)k[11])<<24;
+      mix(a,b,c);
+      length -= 12;
+      k += 12;
+    }
+
+    /*-------------------------------- last block: affect all 32 bits of (c) */
+    switch(length)                   /* all the case statements fall through */
+    {
+    case 12: c+=((uint32_t)k[11])<<24;
+    case 11: c+=((uint32_t)k[10])<<16;
+    case 10: c+=((uint32_t)k[9])<<8;
+    case 9 : c+=k[8];
+    case 8 : b+=((uint32_t)k[7])<<24;
+    case 7 : b+=((uint32_t)k[6])<<16;
+    case 6 : b+=((uint32_t)k[5])<<8;
+    case 5 : b+=k[4];
+    case 4 : a+=((uint32_t)k[3])<<24;
+    case 3 : a+=((uint32_t)k[2])<<16;
+    case 2 : a+=((uint32_t)k[1])<<8;
+    case 1 : a+=k[0];
+             break;
+    case 0 : *pc=c; *pb=b; return;  /* zero length strings require no mixing */
+    }
+  }
+
+  final(a,b,c);
+  *pc=c; *pb=b;
+}
+
+
+
+/*
+ * hashbig():
+ * This is the same as hashword() on big-endian machines.  It is different
+ * from hashlittle() on all machines.  hashbig() takes advantage of
+ * big-endian byte ordering. 
+ */
+uint32_t hashbig( const void *key, size_t length, uint32_t initval)
+{
+  uint32_t a,b,c;
+  union { const void *ptr; size_t i; } u; /* to cast key to (size_t) happily */
+
+  /* Set up the internal state */
+  a = b = c = 0xdeadbeef + ((uint32_t)length) + initval;
+
+  u.ptr = key;
+  if (HASH_BIG_ENDIAN && ((u.i & 0x3) == 0)) {
+    const uint32_t *k = (const uint32_t *)key;         /* read 32-bit chunks */
+    const uint8_t  *k8;
+
+    /*------ all but last block: aligned reads and affect 32 bits of (a,b,c) */
+    while (length > 12)
+    {
+      a += k[0];
+      b += k[1];
+      c += k[2];
+      mix(a,b,c);
+      length -= 12;
+      k += 3;
+    }
+
+    /*----------------------------- handle the last (probably partial) block */
+    /* 
+     * "k[2]<<8" actually reads beyond the end of the string, but
+     * then shifts out the part it's not allowed to read.  Because the
+     * string is aligned, the illegal read is in the same word as the
+     * rest of the string.  Every machine with memory protection I've seen
+     * does it on word boundaries, so is OK with this.  But VALGRIND will
+     * still catch it and complain.  The masking trick does make the hash
+     * noticably faster for short strings (like English words).
+     */
+#ifndef VALGRIND
+
+    switch(length)
+    {
+    case 12: c+=k[2]; b+=k[1]; a+=k[0]; break;
+    case 11: c+=k[2]&0xffffff00; b+=k[1]; a+=k[0]; break;
+    case 10: c+=k[2]&0xffff0000; b+=k[1]; a+=k[0]; break;
+    case 9 : c+=k[2]&0xff000000; b+=k[1]; a+=k[0]; break;
+    case 8 : b+=k[1]; a+=k[0]; break;
+    case 7 : b+=k[1]&0xffffff00; a+=k[0]; break;
+    case 6 : b+=k[1]&0xffff0000; a+=k[0]; break;
+    case 5 : b+=k[1]&0xff000000; a+=k[0]; break;
+    case 4 : a+=k[0]; break;
+    case 3 : a+=k[0]&0xffffff00; break;
+    case 2 : a+=k[0]&0xffff0000; break;
+    case 1 : a+=k[0]&0xff000000; break;
+    case 0 : return c;              /* zero length strings require no mixing */
+    }
+
+#else  /* make valgrind happy */
+
+    k8 = (const uint8_t *)k;
+    switch(length)                   /* all the case statements fall through */
+    {
+    case 12: c+=k[2]; b+=k[1]; a+=k[0]; break;
+    case 11: c+=((uint32_t)k8[10])<<8;  /* fall through */
+    case 10: c+=((uint32_t)k8[9])<<16;  /* fall through */
+    case 9 : c+=((uint32_t)k8[8])<<24;  /* fall through */
+    case 8 : b+=k[1]; a+=k[0]; break;
+    case 7 : b+=((uint32_t)k8[6])<<8;   /* fall through */
+    case 6 : b+=((uint32_t)k8[5])<<16;  /* fall through */
+    case 5 : b+=((uint32_t)k8[4])<<24;  /* fall through */
+    case 4 : a+=k[0]; break;
+    case 3 : a+=((uint32_t)k8[2])<<8;   /* fall through */
+    case 2 : a+=((uint32_t)k8[1])<<16;  /* fall through */
+    case 1 : a+=((uint32_t)k8[0])<<24; break;
+    case 0 : return c;
+    }
+
+#endif /* !VALGRIND */
+
+  } else {                        /* need to read the key one byte at a time */
+    const uint8_t *k = (const uint8_t *)key;
+
+    /*--------------- all but the last block: affect some 32 bits of (a,b,c) */
+    while (length > 12)
+    {
+      a += ((uint32_t)k[0])<<24;
+      a += ((uint32_t)k[1])<<16;
+      a += ((uint32_t)k[2])<<8;
+      a += ((uint32_t)k[3]);
+      b += ((uint32_t)k[4])<<24;
+      b += ((uint32_t)k[5])<<16;
+      b += ((uint32_t)k[6])<<8;
+      b += ((uint32_t)k[7]);
+      c += ((uint32_t)k[8])<<24;
+      c += ((uint32_t)k[9])<<16;
+      c += ((uint32_t)k[10])<<8;
+      c += ((uint32_t)k[11]);
+      mix(a,b,c);
+      length -= 12;
+      k += 12;
+    }
+
+    /*-------------------------------- last block: affect all 32 bits of (c) */
+    switch(length)                   /* all the case statements fall through */
+    {
+    case 12: c+=k[11];
+    case 11: c+=((uint32_t)k[10])<<8;
+    case 10: c+=((uint32_t)k[9])<<16;
+    case 9 : c+=((uint32_t)k[8])<<24;
+    case 8 : b+=k[7];
+    case 7 : b+=((uint32_t)k[6])<<8;
+    case 6 : b+=((uint32_t)k[5])<<16;
+    case 5 : b+=((uint32_t)k[4])<<24;
+    case 4 : a+=k[3];
+    case 3 : a+=((uint32_t)k[2])<<8;
+    case 2 : a+=((uint32_t)k[1])<<16;
+    case 1 : a+=((uint32_t)k[0])<<24;
+             break;
+    case 0 : return c;
+    }
+  }
+
+  final(a,b,c);
+  return c;
+}
+
+
+#ifdef SELF_TEST
+
+/* used for timings */
+void driver1()
+{
+  uint8_t buf[256];
+  uint32_t i;
+  uint32_t h=0;
+  time_t a,z;
+
+  time(&a);
+  for (i=0; i<256; ++i) buf[i] = 'x';
+  for (i=0; i<1; ++i) 
+  {
+    h = hashlittle(&buf[0],1,h);
+  }
+  time(&z);
+  if (z-a > 0) printf("time %d %.8x\n", z-a, h);
+}
+
+/* check that every input bit changes every output bit half the time */
+#define HASHSTATE 1
+#define HASHLEN   1
+#define MAXPAIR 60
+#define MAXLEN  70
+void driver2()
+{
+  uint8_t qa[MAXLEN+1], qb[MAXLEN+2], *a = &qa[0], *b = &qb[1];
+  uint32_t c[HASHSTATE], d[HASHSTATE], i=0, j=0, k, l, m=0, z;
+  uint32_t e[HASHSTATE],f[HASHSTATE],g[HASHSTATE],h[HASHSTATE];
+  uint32_t x[HASHSTATE],y[HASHSTATE];
+  uint32_t hlen;
+
+  printf("No more than %d trials should ever be needed \n",MAXPAIR/2);
+  for (hlen=0; hlen < MAXLEN; ++hlen)
+  {
+    z=0;
+    for (i=0; i<hlen; ++i)  /*----------------------- for each input byte, */
+    {
+      for (j=0; j<8; ++j)   /*------------------------ for each input bit, */
+      {
+	for (m=1; m<8; ++m) /*------------ for serveral possible initvals, */
+	{
+	  for (l=0; l<HASHSTATE; ++l)
+	    e[l]=f[l]=g[l]=h[l]=x[l]=y[l]=~((uint32_t)0);
+
+      	  /*---- check that every output bit is affected by that input bit */
+	  for (k=0; k<MAXPAIR; k+=2)
+	  { 
+	    uint32_t finished=1;
+	    /* keys have one bit different */
+	    for (l=0; l<hlen+1; ++l) {a[l] = b[l] = (uint8_t)0;}
+	    /* have a and b be two keys differing in only one bit */
+	    a[i] ^= (k<<j);
+	    a[i] ^= (k>>(8-j));
+	     c[0] = hashlittle(a, hlen, m);
+	    b[i] ^= ((k+1)<<j);
+	    b[i] ^= ((k+1)>>(8-j));
+	     d[0] = hashlittle(b, hlen, m);
+	    /* check every bit is 1, 0, set, and not set at least once */
+	    for (l=0; l<HASHSTATE; ++l)
+	    {
+	      e[l] &= (c[l]^d[l]);
+	      f[l] &= ~(c[l]^d[l]);
+	      g[l] &= c[l];
+	      h[l] &= ~c[l];
+	      x[l] &= d[l];
+	      y[l] &= ~d[l];
+	      if (e[l]|f[l]|g[l]|h[l]|x[l]|y[l]) finished=0;
+	    }
+	    if (finished) break;
+	  }
+	  if (k>z) z=k;
+	  if (k==MAXPAIR) 
+	  {
+	     printf("Some bit didn't change: ");
+	     printf("%.8x %.8x %.8x %.8x %.8x %.8x  ",
+	            e[0],f[0],g[0],h[0],x[0],y[0]);
+	     printf("i %d j %d m %d len %d\n", i, j, m, hlen);
+	  }
+	  if (z==MAXPAIR) goto done;
+	}
+      }
+    }
+   done:
+    if (z < MAXPAIR)
+    {
+      printf("Mix success  %2d bytes  %2d initvals  ",i,m);
+      printf("required  %d  trials\n", z/2);
+    }
+  }
+  printf("\n");
+}
+
+/* Check for reading beyond the end of the buffer and alignment problems */
+void driver3()
+{
+  uint8_t buf[MAXLEN+20], *b;
+  uint32_t len;
+  uint8_t q[] = "This is the time for all good men to come to the aid of their country...";
+  uint32_t h;
+  uint8_t qq[] = "xThis is the time for all good men to come to the aid of their country...";
+  uint32_t i;
+  uint8_t qqq[] = "xxThis is the time for all good men to come to the aid of their country...";
+  uint32_t j;
+  uint8_t qqqq[] = "xxxThis is the time for all good men to come to the aid of their country...";
+  uint32_t ref,x,y;
+  uint8_t *p;
+
+  printf("Endianness.  These lines should all be the same (for values filled in):\n");
+  printf("%.8x                            %.8x                            %.8x\n",
+         hashword((const uint32_t *)q, (sizeof(q)-1)/4, 13),
+         hashword((const uint32_t *)q, (sizeof(q)-5)/4, 13),
+         hashword((const uint32_t *)q, (sizeof(q)-9)/4, 13));
+  p = q;
+  printf("%.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x\n",
+         hashlittle(p, sizeof(q)-1, 13), hashlittle(p, sizeof(q)-2, 13),
+         hashlittle(p, sizeof(q)-3, 13), hashlittle(p, sizeof(q)-4, 13),
+         hashlittle(p, sizeof(q)-5, 13), hashlittle(p, sizeof(q)-6, 13),
+         hashlittle(p, sizeof(q)-7, 13), hashlittle(p, sizeof(q)-8, 13),
+         hashlittle(p, sizeof(q)-9, 13), hashlittle(p, sizeof(q)-10, 13),
+         hashlittle(p, sizeof(q)-11, 13), hashlittle(p, sizeof(q)-12, 13));
+  p = &qq[1];
+  printf("%.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x\n",
+         hashlittle(p, sizeof(q)-1, 13), hashlittle(p, sizeof(q)-2, 13),
+         hashlittle(p, sizeof(q)-3, 13), hashlittle(p, sizeof(q)-4, 13),
+         hashlittle(p, sizeof(q)-5, 13), hashlittle(p, sizeof(q)-6, 13),
+         hashlittle(p, sizeof(q)-7, 13), hashlittle(p, sizeof(q)-8, 13),
+         hashlittle(p, sizeof(q)-9, 13), hashlittle(p, sizeof(q)-10, 13),
+         hashlittle(p, sizeof(q)-11, 13), hashlittle(p, sizeof(q)-12, 13));
+  p = &qqq[2];
+  printf("%.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x\n",
+         hashlittle(p, sizeof(q)-1, 13), hashlittle(p, sizeof(q)-2, 13),
+         hashlittle(p, sizeof(q)-3, 13), hashlittle(p, sizeof(q)-4, 13),
+         hashlittle(p, sizeof(q)-5, 13), hashlittle(p, sizeof(q)-6, 13),
+         hashlittle(p, sizeof(q)-7, 13), hashlittle(p, sizeof(q)-8, 13),
+         hashlittle(p, sizeof(q)-9, 13), hashlittle(p, sizeof(q)-10, 13),
+         hashlittle(p, sizeof(q)-11, 13), hashlittle(p, sizeof(q)-12, 13));
+  p = &qqqq[3];
+  printf("%.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x %.8x\n",
+         hashlittle(p, sizeof(q)-1, 13), hashlittle(p, sizeof(q)-2, 13),
+         hashlittle(p, sizeof(q)-3, 13), hashlittle(p, sizeof(q)-4, 13),
+         hashlittle(p, sizeof(q)-5, 13), hashlittle(p, sizeof(q)-6, 13),
+         hashlittle(p, sizeof(q)-7, 13), hashlittle(p, sizeof(q)-8, 13),
+         hashlittle(p, sizeof(q)-9, 13), hashlittle(p, sizeof(q)-10, 13),
+         hashlittle(p, sizeof(q)-11, 13), hashlittle(p, sizeof(q)-12, 13));
+  printf("\n");
+
+  /* check that hashlittle2 and hashlittle produce the same results */
+  i=47; j=0;
+  hashlittle2(q, sizeof(q), &i, &j);
+  if (hashlittle(q, sizeof(q), 47) != i)
+    printf("hashlittle2 and hashlittle mismatch\n");
+
+  /* check that hashword2 and hashword produce the same results */
+  len = 0xdeadbeef;
+  i=47, j=0;
+  hashword2(&len, 1, &i, &j);
+  if (hashword(&len, 1, 47) != i)
+    printf("hashword2 and hashword mismatch %x %x\n", 
+	   i, hashword(&len, 1, 47));
+
+  /* check hashlittle doesn't read before or after the ends of the string */
+  for (h=0, b=buf+1; h<8; ++h, ++b)
+  {
+    for (i=0; i<MAXLEN; ++i)
+    {
+      len = i;
+      for (j=0; j<i; ++j) *(b+j)=0;
+
+      /* these should all be equal */
+      ref = hashlittle(b, len, (uint32_t)1);
+      *(b+i)=(uint8_t)~0;
+      *(b-1)=(uint8_t)~0;
+      x = hashlittle(b, len, (uint32_t)1);
+      y = hashlittle(b, len, (uint32_t)1);
+      if ((ref != x) || (ref != y)) 
+      {
+	printf("alignment error: %.8x %.8x %.8x %d %d\n",ref,x,y,
+               h, i);
+      }
+    }
+  }
+}
+
+/* check for problems with nulls */
+ void driver4()
+{
+  uint8_t buf[1];
+  uint32_t h,i,state[HASHSTATE];
+
+
+  buf[0] = ~0;
+  for (i=0; i<HASHSTATE; ++i) state[i] = 1;
+  printf("These should all be different\n");
+  for (i=0, h=0; i<8; ++i)
+  {
+    h = hashlittle(buf, 0, h);
+    printf("%2ld  0-byte strings, hash is  %.8x\n", i, h);
+  }
+}
+
+void driver5()
+{
+  uint32_t b,c;
+  b=0, c=0, hashlittle2("", 0, &c, &b);
+  printf("hash is %.8lx %.8lx\n", c, b);   /* deadbeef deadbeef */
+  b=0xdeadbeef, c=0, hashlittle2("", 0, &c, &b);
+  printf("hash is %.8lx %.8lx\n", c, b);   /* bd5b7dde deadbeef */
+  b=0xdeadbeef, c=0xdeadbeef, hashlittle2("", 0, &c, &b);
+  printf("hash is %.8lx %.8lx\n", c, b);   /* 9c093ccd bd5b7dde */
+  b=0, c=0, hashlittle2("Four score and seven years ago", 30, &c, &b);
+  printf("hash is %.8lx %.8lx\n", c, b);   /* 17770551 ce7226e6 */
+  b=1, c=0, hashlittle2("Four score and seven years ago", 30, &c, &b);
+  printf("hash is %.8lx %.8lx\n", c, b);   /* e3607cae bd371de4 */
+  b=0, c=1, hashlittle2("Four score and seven years ago", 30, &c, &b);
+  printf("hash is %.8lx %.8lx\n", c, b);   /* cd628161 6cbea4b3 */
+  c = hashlittle("Four score and seven years ago", 30, 0);
+  printf("hash is %.8lx\n", c);   /* 17770551 */
+  c = hashlittle("Four score and seven years ago", 30, 1);
+  printf("hash is %.8lx\n", c);   /* cd628161 */
+}
+
+
+int main()
+{
+  driver1();   /* test that the key is hashed: used for timings */
+  driver2();   /* test that whole key is hashed thoroughly */
+  driver3();   /* test that nothing but the key is hashed */
+  driver4();   /* test hashing multiple buffers (all buffers are null) */
+  driver5();   /* test the hash against known vectors */
+  return 1;
+}
+
+#endif  /* SELF_TEST */