greatly simplify compressor loop

thanks byuu!
master
Connor Olding 4 years ago
parent 155682e209
commit c771a718b7
  1. 148
      compressor.c

@ -1,15 +1,9 @@
//#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef unsigned char u8;
typedef unsigned int u32;
#define MIN(a, b) ((a) <= (b) ? (a) : (b))
#define MAX(a, b) ((a) >= (b) ? (a) : (b))
#define PMOD(a, b) (((a) + (b)) % (b))
#ifdef _WIN32
#define FMT_SIZE "%Iu"
@ -31,108 +25,52 @@ typedef unsigned int u32;
#define MAX_LEN 66
#define BUF_START 0x3BE
#ifndef RW_OVERLAP
#define RW_OVERLAP 1
#endif
long compress(const u8 *bufi, long size, u8 *bufo) {
// this function cannot fail.
// just ensure bufo points to enough memory to hold the compressed data.
u8 buf[BUF_LEN] = {0};
int buf_i = BUF_START;
int shift = 0;
int shifted = 0;
int last_shift_i = -1;
long written = 0;
int compress(const u8 *bufi, int size, u8 *bufo) {
int i = 0;
int written = 0;
while (i < size) {
const u8 *sub = bufi + i;
int sub_len = MIN(MAX_LEN, size - i);
int best_i = -1;
int best_len = -1;
if (sub_len >= MIN_LEN) {
for (int j = 0; j < BUF_LEN; j++) {
int match_i = PMOD(buf_i - j, BUF_LEN);
int match_len = 0;
#if RW_OVERLAP
int overlap = 0;
#endif
for (;;) {
int buf_off = (match_i + match_len) % BUF_LEN;
#if RW_OVERLAP
if (overlap > 0 || (buf_off == buf_i && j != 0)) {
if (sub[overlap % j] != sub[match_len]) break;
overlap++;
} else {
if (buf[buf_off] != sub[match_len]) break;
}
#else
if (buf_off == buf_i && j != 0) break;
if (buf[buf_off] != sub[match_len]) break;
#endif
match_len++;
if (match_len == MAX_LEN) break;
if (match_len == sub_len) break;
int flag_i = written;
int flags = 0x00;
bufo[written++] = 0;
for (int j = 0; j < 8; j++) {
if (i == size) break;
int best_match = 0;
int best_len = 0;
for (int match = BUF_LEN; match > 0; match--) {
int len = 0;
int left = i - match;
int right = i;
while (bufi[left++] == bufi[right++]) {
if (left == i) left -= match;
len++;
if (right >= size) break;
if (len >= MAX_LEN) break;
}
if (match_len < MIN_LEN) continue;
if (match_len > best_len) {
best_i = match_i;
best_len = match_len;
if (len > best_len) {
best_len = len;
best_match = match;
if (len == MAX_LEN) break;
}
}
}
if (last_shift_i < 0) {
last_shift_i = written;
bufo[written++] = 0;
shift = 0;
shifted = 0;
}
if (best_i < 0 || best_len < 0) {
shift >>= 1;
shift |= 0x80;
shifted++;
bufo[written++] = sub[0];
buf[buf_i] = sub[0];
buf_i = (buf_i + 1) % BUF_LEN;
i++;
} else {
shift >>= 1;
shifted++;
u8 a = best_i & 0xFF;
u8 b = ((best_i & 0x300) >> 2) | (best_len - 3);
bufo[written++] = a;
bufo[written++] = b;
for (int j = 0; j < best_len; j++) {
buf[buf_i] = sub[j];
buf_i = (buf_i + 1) % BUF_LEN;
if (best_len < MIN_LEN) {
flags |= 1 << j;
bufo[written++] = bufi[i++];
} else {
int buf_match = (i + BUF_START - best_match) & 0x3FF;
//lament("$%03X:%i\n", buf_match, best_len);
int a = buf_match & 0xFF;
int b = ((buf_match & 0x300) >> 2) | (best_len - 3);
bufo[written++] = a;
bufo[written++] = b;
i += best_len;
}
i += best_len;
}
if (shifted >= 8) {
//assert(last_shift_i != -1);
bufo[last_shift_i] = shift;
shift = 0;
shifted = 0;
last_shift_i = -1;
}
bufo[flag_i] = flags;
}
if (last_shift_i >= 0) {
bufo[last_shift_i] = shift >> (8 - shifted);
}
//assert(i == size);
return written;
}
@ -155,9 +93,10 @@ int compress_file(const char *fp) {
error_when(fseek(f, 0, SEEK_SET) != 0, "Error seeking in file: %s", fp);
if (size > 0) {
bufi = (u8 *)malloc(size);
error_when(bufi == NULL, "Error allocating %li bytes", size);
error_when(fread(bufi, 1, size, f) != (size_t)size, "Error reading %li bytes from file: %s", size, fp);
bufi = (u8 *)malloc(size + BUF_LEN);
for (int i = 0; i < BUF_LEN; i++) bufi[i] = 0;
error_when(bufi == NULL, "Error allocating %li bytes", size + BUF_LEN);
error_when(fread(bufi + BUF_LEN, 1, size, f) != (size_t)size, "Error reading %li bytes from file: %s", size, fp);
}
error_when(fclose(f) != 0, "Error closing file: %s", fp);
@ -167,9 +106,7 @@ int compress_file(const char *fp) {
size_t bufo_size = size * 9 / 8 + 8;
bufo = (u8 *)malloc(bufo_size);
error_when(bufo == NULL, "Error allocating " FMT_SIZE " bytes", bufo_size);
new_size = compress(bufi, size, bufo);
//assert(new_size > 0 && (size_t)new_size < bufo_size);
new_size = compress(bufi + BUF_LEN, size, bufo);
}
f = fopen(fp, "wb");
@ -204,7 +141,8 @@ int main(int argc, char *argv[]) {
}
const char *name = argv[0];
if (argc == 1) {
lament("compressor: compress files in-place for Bomberman 64.\n");
lament("compressor: compress files in-place with LZSS\n");
lament("compatible with Bomberman 64 and Mario Party 1\n");
lament("usage: %s {file}\n", name);
return 1;
} else if (argc == 2) {

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