--- /dev/null
+#include "platform.h"
+#include <stdio.h>
+#include <stdarg.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <assert.h>
+
+#include "rans_byte.h"
+
+// This is just the sample program. All the meat is in rans_byte.h.
+
+static void panic(const char *fmt, ...)
+{
+ va_list arg;
+
+ va_start(arg, fmt);
+ fputs("Error: ", stderr);
+ vfprintf(stderr, fmt, arg);
+ va_end(arg);
+ fputs("\n", stderr);
+
+ exit(1);
+}
+
+static uint8_t* read_file(char const* filename, size_t* out_size)
+{
+ FILE* f = fopen(filename, "rb");
+ if (!f)
+ panic("file not found: %s\n", filename);
+
+ fseek(f, 0, SEEK_END);
+ size_t size = ftell(f);
+ fseek(f, 0, SEEK_SET);
+
+ uint8_t* buf = new uint8_t[size];
+ if (fread(buf, size, 1, f) != 1)
+ panic("read failed\n");
+
+ fclose(f);
+ if (out_size)
+ *out_size = size;
+
+ return buf;
+}
+
+// ---- Stats
+
+struct SymbolStats
+{
+ uint32_t freqs[256];
+ uint32_t cum_freqs[257];
+
+ void count_freqs(uint8_t const* in, size_t nbytes);
+ void calc_cum_freqs();
+ void normalize_freqs(uint32_t target_total);
+};
+
+void SymbolStats::count_freqs(uint8_t const* in, size_t nbytes)
+{
+ for (int i=0; i < 256; i++)
+ freqs[i] = 0;
+
+ for (size_t i=0; i < nbytes; i++)
+ freqs[in[i]]++;
+}
+
+void SymbolStats::calc_cum_freqs()
+{
+ cum_freqs[0] = 0;
+ for (int i=0; i < 256; i++)
+ cum_freqs[i+1] = cum_freqs[i] + freqs[i];
+}
+
+void SymbolStats::normalize_freqs(uint32_t target_total)
+{
+ assert(target_total >= 256);
+
+ calc_cum_freqs();
+ uint32_t cur_total = cum_freqs[256];
+
+ // resample distribution based on cumulative freqs
+ for (int i = 1; i <= 256; i++)
+ cum_freqs[i] = ((uint64_t)target_total * cum_freqs[i])/cur_total;
+
+ // if we nuked any non-0 frequency symbol to 0, we need to steal
+ // the range to make the frequency nonzero from elsewhere.
+ //
+ // this is not at all optimal, i'm just doing the first thing that comes to mind.
+ for (int i=0; i < 256; i++) {
+ if (freqs[i] && cum_freqs[i+1] == cum_freqs[i]) {
+ // symbol i was set to zero freq
+
+ // find best symbol to steal frequency from (try to steal from low-freq ones)
+ uint32_t best_freq = ~0u;
+ int best_steal = -1;
+ for (int j=0; j < 256; j++) {
+ uint32_t freq = cum_freqs[j+1] - cum_freqs[j];
+ if (freq > 1 && freq < best_freq) {
+ best_freq = freq;
+ best_steal = j;
+ }
+ }
+ assert(best_steal != -1);
+
+ // and steal from it!
+ if (best_steal < i) {
+ for (int j = best_steal + 1; j <= i; j++)
+ cum_freqs[j]--;
+ } else {
+ assert(best_steal > i);
+ for (int j = i + 1; j <= best_steal; j++)
+ cum_freqs[j]++;
+ }
+ }
+ }
+
+ // calculate updated freqs and make sure we didn't screw anything up
+ assert(cum_freqs[0] == 0 && cum_freqs[256] == target_total);
+ for (int i=0; i < 256; i++) {
+ if (freqs[i] == 0)
+ assert(cum_freqs[i+1] == cum_freqs[i]);
+ else
+ assert(cum_freqs[i+1] > cum_freqs[i]);
+
+ // calc updated freq
+ freqs[i] = cum_freqs[i+1] - cum_freqs[i];
+ }
+}
+
+int main()
+{
+ size_t in_size;
+ uint8_t* in_bytes = read_file("book1", &in_size);
+
+ static const uint32_t prob_bits = 14;
+ static const uint32_t prob_scale = 1 << prob_bits;
+
+ SymbolStats stats;
+ stats.count_freqs(in_bytes, in_size);
+ stats.normalize_freqs(prob_scale);
+
+ // cumlative->symbol table
+ // this is super brute force
+ uint8_t cum2sym[prob_scale];
+ for (int s=0; s < 256; s++)
+ for (uint32_t i=stats.cum_freqs[s]; i < stats.cum_freqs[s+1]; i++)
+ cum2sym[i] = s;
+
+ static size_t out_max_size = 32<<20; // 32MB
+ uint8_t* out_buf = new uint8_t[out_max_size];
+ uint8_t* dec_bytes = new uint8_t[in_size];
+
+ // try rANS encode
+ uint8_t *rans_begin;
+ RansEncSymbol esyms[256];
+ RansDecSymbol dsyms[256];
+
+ for (int i=0; i < 256; i++) {
+ RansEncSymbolInit(&esyms[i], stats.cum_freqs[i], stats.freqs[i], prob_bits);
+ RansDecSymbolInit(&dsyms[i], stats.cum_freqs[i], stats.freqs[i]);
+ }
+
+ // ---- regular rANS encode/decode. Typical usage.
+
+ memset(dec_bytes, 0xcc, in_size);
+
+ printf("rANS encode:\n");
+ for (int run=0; run < 5; run++) {
+ double start_time = timer();
+ uint64_t enc_start_time = __rdtsc();
+
+ RansState rans;
+ RansEncInit(&rans);
+
+ uint8_t* ptr = out_buf + out_max_size; // *end* of output buffer
+ for (size_t i=in_size; i > 0; i--) { // NB: working in reverse!
+ int s = in_bytes[i-1];
+ RansEncPutSymbol(&rans, &ptr, &esyms[s]);
+ }
+ RansEncFlush(&rans, &ptr);
+ rans_begin = ptr;
+
+ uint64_t enc_clocks = __rdtsc() - enc_start_time;
+ double enc_time = timer() - start_time;
+ printf("%"PRIu64" clocks, %.1f clocks/symbol (%5.1fMiB/s)\n", enc_clocks, 1.0 * enc_clocks / in_size, 1.0 * in_size / (enc_time * 1048576.0));
+ }
+ printf("rANS: %d bytes\n", (int) (out_buf + out_max_size - rans_begin));
+
+ // try rANS decode
+ for (int run=0; run < 5; run++) {
+ double start_time = timer();
+ uint64_t dec_start_time = __rdtsc();
+
+ RansState rans;
+ uint8_t* ptr = rans_begin;
+ RansDecInit(&rans, &ptr);
+
+ for (size_t i=0; i < in_size; i++) {
+ uint32_t s = cum2sym[RansDecGet(&rans, prob_bits)];
+ dec_bytes[i] = (uint8_t) s;
+ RansDecAdvanceSymbol(&rans, &ptr, &dsyms[s], prob_bits);
+ }
+
+ uint64_t dec_clocks = __rdtsc() - dec_start_time;
+ double dec_time = timer() - start_time;
+ printf("%"PRIu64" clocks, %.1f clocks/symbol (%5.1fMiB/s)\n", dec_clocks, 1.0 * dec_clocks / in_size, 1.0 * in_size / (dec_time * 1048576.0));
+ }
+
+ // check decode results
+ if (memcmp(in_bytes, dec_bytes, in_size) == 0)
+ printf("decode ok!\n");
+ else
+ printf("ERROR: bad decoder!\n");
+
+ // ---- interleaved rANS encode/decode. This is the kind of thing you might do to optimize critical paths.
+
+ memset(dec_bytes, 0xcc, in_size);
+
+ // try interleaved rANS encode
+ printf("\ninterleaved rANS encode:\n");
+ for (int run=0; run < 5; run++) {
+ double start_time = timer();
+ uint64_t enc_start_time = __rdtsc();
+
+ RansState rans0, rans1;
+ RansEncInit(&rans0);
+ RansEncInit(&rans1);
+
+ uint8_t* ptr = out_buf + out_max_size; // *end* of output buffer
+
+ // odd number of bytes?
+ if (in_size & 1) {
+ int s = in_bytes[in_size - 1];
+ RansEncPutSymbol(&rans0, &ptr, &esyms[s]);
+ }
+
+ for (size_t i=(in_size & ~1); i > 0; i -= 2) { // NB: working in reverse!
+ int s1 = in_bytes[i-1];
+ int s0 = in_bytes[i-2];
+ RansEncPutSymbol(&rans1, &ptr, &esyms[s1]);
+ RansEncPutSymbol(&rans0, &ptr, &esyms[s0]);
+ }
+ RansEncFlush(&rans1, &ptr);
+ RansEncFlush(&rans0, &ptr);
+ rans_begin = ptr;
+
+ uint64_t enc_clocks = __rdtsc() - enc_start_time;
+ double enc_time = timer() - start_time;
+ printf("%"PRIu64" clocks, %.1f clocks/symbol (%5.1fMiB/s)\n", enc_clocks, 1.0 * enc_clocks / in_size, 1.0 * in_size / (enc_time * 1048576.0));
+ }
+ printf("interleaved rANS: %d bytes\n", (int) (out_buf + out_max_size - rans_begin));
+
+ // try interleaved rANS decode
+ for (int run=0; run < 5; run++) {
+ double start_time = timer();
+ uint64_t dec_start_time = __rdtsc();
+
+ RansState rans0, rans1;
+ uint8_t* ptr = rans_begin;
+ RansDecInit(&rans0, &ptr);
+ RansDecInit(&rans1, &ptr);
+
+ for (size_t i=0; i < (in_size & ~1); i += 2) {
+ uint32_t s0 = cum2sym[RansDecGet(&rans0, prob_bits)];
+ uint32_t s1 = cum2sym[RansDecGet(&rans1, prob_bits)];
+ dec_bytes[i+0] = (uint8_t) s0;
+ dec_bytes[i+1] = (uint8_t) s1;
+ RansDecAdvanceSymbolStep(&rans0, &dsyms[s0], prob_bits);
+ RansDecAdvanceSymbolStep(&rans1, &dsyms[s1], prob_bits);
+ RansDecRenorm(&rans0, &ptr);
+ RansDecRenorm(&rans1, &ptr);
+ }
+
+ // last byte, if number of bytes was odd
+ if (in_size & 1) {
+ uint32_t s0 = cum2sym[RansDecGet(&rans0, prob_bits)];
+ dec_bytes[in_size - 1] = (uint8_t) s0;
+ RansDecAdvanceSymbol(&rans0, &ptr, &dsyms[s0], prob_bits);
+ }
+
+ uint64_t dec_clocks = __rdtsc() - dec_start_time;
+ double dec_time = timer() - start_time;
+ printf("%"PRIu64" clocks, %.1f clocks/symbol (%5.1fMB/s)\n", dec_clocks, 1.0 * dec_clocks / in_size, 1.0 * in_size / (dec_time * 1048576.0));
+ }
+
+ // check decode results
+ if (memcmp(in_bytes, dec_bytes, in_size) == 0)
+ printf("decode ok!\n");
+ else
+ printf("ERROR: bad decoder!\n");
+
+ delete[] out_buf;
+ delete[] dec_bytes;
+ delete[] in_bytes;
+ return 0;
+}
projects / narabu / blobdiff