add test code and sample table builder script

support setting a non-zero base for freq. table


git-svn-id: http://svn.coderepos.org/share/lang/cplusplus/range_coder@7156 d0d07461-0603-4401-acd4-de1884942a52

bench.cpp

@@ -0,0 +1,83 @@
+extern "C" {
+#include <assert.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+}
+#include <algorithm>
+#include "range_coder.hpp"
+
+#include "table.c"
+
+class writer_t {
+  char **p, *max;
+public:
+  struct overrun_t {
+  };
+  writer_t(char **_p, char *_max) : p(_p), max(_max) {}
+  writer_t &operator=(char c) {
+    if (*p == max) {
+      throw overrun_t();
+    }
+    *(*p)++ = c;
+    return *this;
+  }
+  writer_t &operator*() { return *this; }
+  writer_t &operator++() { return *this; }
+  writer_t &operator++(int) { return *this; }
+};
+
+#define FREQ_BASE SHRT_MIN
+#define LOOP_CNT 1024
+
+int main(int argc, char **argv)
+{
+  char buf[1024 * 1024], cbuf[1024 * 1024], rbuf[1024 * 1024];
+  size_t buflen, cbuflen;
+  unsigned long long start;
+  int i;
+
+  /* read */
+  buflen = fread(buf, 1, sizeof(buf) - 1, stdin);
+  /* compress */
+  start = rdtsc();
+  for (i = 0; i < LOOP_CNT; i++) {
+    char *cbufpt = cbuf;
+    rc_encoder_t<writer_t> enc(writer_t(&cbufpt, cbuf + sizeof(cbuf)));
+    for (const char *p = buf, *e = buf + buflen; p != e; p++) {
+      unsigned ch = (unsigned char)*p;
+#ifdef USE_ORDERED_TABLE
+      ch = to_ordered[ch];
+#endif
+      assert(freq[ch] != freq[ch + 1]);
+      enc.encode(freq[ch] - FREQ_BASE, freq[ch + 1] - FREQ_BASE,
+		 freq[256] - FREQ_BASE);
+    }
+    enc.final();
+    cbuflen = cbufpt - cbuf;
+  }
+  printf("compression: %lu Mticks\n", (long)((rdtsc() - start) / 1024 / 1024));
+  /* decompress */
+  start = rdtsc();
+  for (i = 0; i < LOOP_CNT; i++) {
+    rc_decoder_t<const char*, rc_decoder_search_t<short, 256, FREQ_BASE> >
+      dec(cbuf, cbuf + cbuflen);
+    for (char *p = rbuf, *e = rbuf + buflen; p != e; p++) {
+      unsigned ch = dec.decode(freq[256] - FREQ_BASE, freq);
+#ifdef USE_ORDERED_TABLE
+      ch = from_ordered[ch];
+#endif
+      *p = ch;
+    }
+  }
+  printf("decompression: %lu Mticks\n",
+	 (long)((rdtsc() - start) / 1024 / 1024));
+  /* check result */
+  if (memcmp(buf, rbuf, buflen) != 0) {
+    fprintf(stderr, "original data and decompressed data does not match.\n");
+    exit(99);
+  }
+
+  return 0;
+}

build_table.pl

@@ -0,0 +1,42 @@
+#! /usr/bin/perl
+
+use strict;
+use warnings;
+
+use Getopt::Long;
+use List::Util qw/sum/;
+
+my ($do_ordered);
+
+GetOptions(
+    'ordered' => \$do_ordered,
+);
+
+
+my @cnt = map { 0 } 0..255;
+
+while (<>) {
+    foreach my $c (split '', $_) {
+        $cnt[ord $c]++;
+    }
+}
+
+if ($do_ordered) {
+    my @order = sort { $cnt[$b] <=> $cnt[$a] } 0..255;
+    print "#define USE_ORDERED_TABLE 1\n";
+    print "static unsigned char from_ordered[] = {", join(',', @order), "};\n";
+    my %r = map { $order[$_] => $_ } @order;
+    print "static unsigned char to_ordered[] = {", join(',', map { $r{$_} } 0..255), "};\n";
+    @cnt = map { $cnt[$order[$_]] } 0..255;
+}
+
+my @freq;
+my $acc = 0;
+my $cc = sum @cnt;
+for (my $i = 0; $i < 256; $i++) {
+    push @freq, $acc;
+    $acc += int(($cnt[$i] / $cc) * 0xfe00);
+}
+push @freq, $acc;
+
+print "static short freq[] __attribute__((aligned(16))) = {", join(',', map { $_ - 0x8000 } @freq), "};\n";

range_coder.hpp

@@ -89,35 +89,34 @@ template <class Iter> class rc_encoder_t : public rc_type_t {
   uint counter;
 };
 
-template <typename FreqType, unsigned _N> struct rc_decoder_search_traits_t : public rc_type_t {
+template <typename FreqType, unsigned _N, int _BASE> struct rc_decoder_search_traits_t : public rc_type_t {
   typedef FreqType freq_type;
   enum {
-    N = _N
+    N = _N,
+    BASE = _BASE
   };
 };
 
-template <typename FreqType, unsigned _N> struct rc_decoder_search_t : public rc_decoder_search_traits_t<FreqType, _N> {
-  static uint get_index(const FreqType *freq, uint pos) {
+template <typename FreqType, unsigned _N, int _BASE = 0> struct rc_decoder_search_t : public rc_decoder_search_traits_t<FreqType, _N, _BASE> {
+  static uint get_index(const FreqType *freq, FreqType pos) {
     uint left  = 0;
     uint right = _N;
     while(left < right) {
       uint mid = (left+right)/2;
-      if (static_cast<uint>(freq[mid+1]) <= pos)
-	left = mid+1;
-      else
-	right = mid;
+      if (freq[mid+1] <= pos) left = mid+1;
+      else                    right = mid;
     }
     return left;
   }
 };
 
 #ifdef RANGE_CODER_USE_SSE
 
-template<> struct rc_decoder_search_t<short, 256> : public rc_decoder_search_traits_t<short, 256> {
-  static uint get_index(const freq_type *freq, uint pos) {
+template<int _BASE> struct rc_decoder_search_t<short, 256, _BASE> : public rc_decoder_search_traits_t<short, 256, _BASE> {
+  static uint get_index(const short *freq, short pos) {
     __m128i v = _mm_set1_epi16(pos);
     unsigned i, mask = 0;
-    for (i = 0; i < N; i += 16) {
+    for (i = 0; i < 256; i += 16) {
       __m128i x = *reinterpret_cast<const __m128i*>(freq + i);
       __m128i y = *reinterpret_cast<const __m128i*>(freq + i + 8);
       __m128i a = _mm_cmplt_epi16(v, x);
@@ -147,12 +146,13 @@ template <class Iterator, class SearchType> class rc_decoder_t : public rc_type_
   }
   uint decode(const uint total, const freq_type* cumFreq) {
     const uint r = R / total;
-    const uint targetPos = std::min(total-1, D / r);
+    const int targetPos = std::min(total-1, D / r);
 
     //find target s.t. cumFreq[target] <= targetPos < cumFreq[target+1]
-    const uint target = search_type::get_index(cumFreq, targetPos);
-    const uint low  = cumFreq[target];
-    const uint high = cumFreq[target+1];
+    const uint target =
+      search_type::get_index(cumFreq, targetPos + search_type::BASE);
+    const uint low  = cumFreq[target] - search_type::BASE;
+    const uint high = cumFreq[target+1] - search_type::BASE;
 
     D -= r * low;
     if (high != total) {