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https://github.com/zeldaret/ph
synced 2026-05-23 15:01:37 -04:00
Implement code compression tool
This commit is contained in:
Aetias
@@ -0,0 +1,2 @@
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compress
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compress.exe
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@@ -0,0 +1,22 @@
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CC := gcc
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CFLAGS := -g
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ifneq ($(DEBUG),1)
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CFLAGS += -O2 -DNDEBUG
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endif
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ifeq ($(OS),Windows_NT)
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OUTFILE := compress.exe
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else
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OUTFILE := compress
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endif
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.PHONY: all clean
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all: $(OUTFILE)
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clean:
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rm $(OUTFILE)
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$(OUTFILE): main.c
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$(CC) $(CFLAGS) -o $(OUTFILE) main.c
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@@ -0,0 +1,226 @@
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// Compresses files using a backwards LZ77 algorithm.
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// This is used to compress code after linking so that the compressed code matches the base ROM.
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#include <stdbool.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#define VERSION "1.0"
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#ifndef min
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# define min(a,b) ((a) < (b) ? (a) : (b))
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#endif
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#define WRITE16(buf,val) do { (buf)[0] = (val) & 0xFF; (buf)[1] = ((val) >> 8) & 0xFF; } while (0)
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#define WRITE24(buf,val) do { (buf)[0] = (val) & 0xFF; (buf)[1] = ((val) >> 8) & 0xFF; (buf)[2] = ((val) >> 16) & 0xFF; } while (0)
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#define WRITE32(buf,val) do { (buf)[0] = (val) & 0xFF; (buf)[1] = ((val) >> 8) & 0xFF; (buf)[2] = ((val) >> 16) & 0xFF; (buf)[3] = ((val) >> 24) & 0xFF; } while (0)
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#define READ16(buf) ((buf)[0] | ((buf)[1] << 8))
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#define READ24(buf) ((buf)[0] | ((buf)[1] << 8) | ((buf)[2] << 16))
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#define READ32(buf) ((buf)[0] | ((buf)[1] << 8) | ((buf)[2] << 16) | ((buf)[3] << 24))
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#define LEN_BITS 4
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#define DIST_BITS 12
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#define MIN_SUBSEQ 3
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#define LEN_MASK ((1 << (LEN_BITS)) - 1)
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#define DIST_MASK ((1 << (DIST_BITS)) - 1)
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#define MAX_SUBSEQ ((MIN_SUBSEQ) + LEN_MASK)
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#define LOOKAHEAD (1 << (DIST_BITS))
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bool FindSubsequence(const uint8_t *buf, const uint8_t *start, const uint8_t *end, size_t *pLen, size_t *pDist) {
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size_t bestLen = 0;
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size_t bestDist = 0;
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size_t maxLookahead = min(LOOKAHEAD + MAX_SUBSEQ, end - buf);
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for (size_t i = 0; i < maxLookahead; ++i) {
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const uint8_t *needle = buf;
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const uint8_t *haystack = buf + 1 + i;
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if (*needle != *haystack) continue;
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size_t len = 0;
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while (needle - len >= start && needle[-len] == haystack[-len] && haystack - len > buf && len < MAX_SUBSEQ) {
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++len;
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}
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size_t dist = haystack - needle - MIN_SUBSEQ;
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if (len > bestLen && dist <= DIST_MASK) {
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bestLen = len;
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bestDist = dist;
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}
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}
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if (bestLen < MIN_SUBSEQ) return false;
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*pLen = bestLen;
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*pDist = bestDist;
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return true;
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}
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bool Compress(const uint8_t *src, uint8_t *dst, size_t size, uint8_t **pResult, size_t *pLen) {
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const uint8_t *end = src + size;
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const uint8_t *read = end;
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uint8_t *write = dst + size - 1;
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uint8_t *pFlags = write;
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uint8_t flags;
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size_t flagCount = 0;
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while (read > src) {
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flags <<= 1;
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size_t len, dist;
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if (FindSubsequence(read - 1, src, end, &len, &dist)) {
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// write length-distance pair
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size_t pair = (((len - MIN_SUBSEQ) & LEN_MASK) << DIST_BITS) | (dist & DIST_MASK);
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read -= len;
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write -= 2;
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WRITE16(write, pair);
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flags |= 1;
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} else {
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// write literal
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write -= 1;
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read -= 1;
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*write = *read;
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}
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flagCount++;
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if (flagCount == 8) {
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flagCount = 0;
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*pFlags = flags;
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flags = 0;
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write -= 1;
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pFlags = write;
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}
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}
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if (flagCount != 0) *pFlags = flags << (8 - flagCount);
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else write += 1;
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*pResult = write;
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*pLen = size - (write - dst);
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return true;
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}
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bool WriteFooter(FILE *fp, const char *fileName, bool addPadding, uint32_t compressedSize, uint32_t originalSize, uint32_t start) {
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size_t padding = 0;
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if (addPadding) padding = 0x10 - (compressedSize & 0xf);
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for (size_t i = 0; i < padding; ++i) fputc(0xFF, fp);
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compressedSize += padding + 8;
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uint32_t readOffset = padding + 8;
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uint32_t writeOffset = originalSize - compressedSize - start;
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if (fwrite(&compressedSize, 3, 1, fp) != 1) {
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if (fp == stdout) fprintf(stderr, "Failed to write compressed size to stdout\n");
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else fprintf(stderr, "Failed to write compressed size to '%s'\n", fileName);
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return false;
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}
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if (fwrite(&readOffset, 1, 1, fp) != 1) {
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if (fp == stdout) fprintf(stderr, "Failed to write read offset to stdout\n");
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else fprintf(stderr, "Failed to write read offset to '%s'\n", fileName);
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return false;
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}
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if (fwrite(&writeOffset, 4, 1, fp) != 1) {
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if (fp == stdout) fprintf(stderr, "Failed to write write offset to stdout\n");
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else fprintf(stderr, "Failed to write write offset to '%s'\n", fileName);
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return false;
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}
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return true;
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}
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void PrintUsage(const char *program) {
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printf(
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"compress " VERSION "\n"
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"\n"
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"Usage: %s [-o OUTFILE] [-s START] [-p] -i INFILE\n"
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" -o OUTFILE\tWrites result to file instead of stdout\n"
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" -s START \tOffset to start compressing from\n"
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" -p \tPad compressed data to 16-alignment\n"
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" -i INFILE \tInput file to compress",
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program
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);
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}
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int main(int argc, const char **argv) {
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const char *program = argv[0];
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if (argc == 1) {
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PrintUsage(program);
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return 0;
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}
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const char *outFile = NULL;
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const char *inFile = NULL;
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int start = 0;
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bool padCompressedBlock = false;
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for (int i = 1; i < argc; ++i) {
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if (strcmp(argv[i], "-o") == 0) {
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if (++i >= argc) {
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fprintf(stderr, "Expected filename after -o\n");
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return 1;
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}
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outFile = argv[i];
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} else if (strcmp(argv[i], "-s") == 0) {
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if (++i >= argc) {
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fprintf(stderr, "Expected start offset after -s\n");
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return 1;
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}
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if (sscanf(argv[i], "%i", &start) != 1) {
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fprintf(stderr, "Invalid start offset '%s' could not be parsed\n", argv[i]);
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return 1;
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}
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} else if (strcmp(argv[i], "-p") == 0) {
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padCompressedBlock = true;
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} else if (strcmp(argv[i], "-i") == 0) {
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if (++i >= argc) {
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fprintf(stderr, "Expected filename after -i\n");
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return 1;
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}
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inFile = argv[i];
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} else {
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fprintf(stderr, "Unknown option '%s'\n", argv[i]);
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return 1;
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}
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}
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if (inFile == NULL) {
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PrintUsage(program);
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fprintf(stderr, "Please provide an input file to compress, see usage above.\n");
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return 1;
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}
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FILE *fpIn = fopen(inFile, "rb");
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if (fpIn == NULL) {
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fprintf(stderr, "Failed to open input file '%s'\n", inFile);
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return 1;
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}
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fseek(fpIn, 0, SEEK_END);
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size_t inSize = ftell(fpIn);
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uint8_t *buf = malloc(inSize);
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if (buf == NULL) {
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fprintf(stderr, "Failed to allocate input buffer for '%s'\n", inFile);
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return 1;
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}
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fseek(fpIn, 0, SEEK_SET);
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if (fread(buf, inSize, 1, fpIn) != 1) {
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fprintf(stderr, "Failed to read input file '%s'\n", inFile);
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return 1;
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}
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fclose(fpIn);
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FILE *fpOut = stdout;
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if (outFile != NULL) {
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fpOut = fopen(outFile, "wb");
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if (fpOut == NULL) {
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fprintf(stderr, "Failed to open output file '%s'\n", outFile);
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return 1;
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}
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}
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if (start > 0 && fwrite(buf, start, 1, fpOut) != 1) {
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if (fpOut == stdout) fprintf(stderr, "Failed to write uncompressed header to stdout\n");
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else fprintf(stderr, "Failed to write uncompressed header to '%s'\n", outFile);
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return 1;
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}
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uint8_t *outBuf = malloc(inSize - start);
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uint8_t *result;
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size_t resultLen;
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if (!Compress(buf + start, outBuf, inSize - start, &result, &resultLen)) return 1;
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if (fwrite(result, resultLen, 1, fpIn) != 1) {
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if (fpOut == stdout) fprintf(stderr, "Failed to write compressed output to stdout\n");
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else fprintf(stderr, "Failed to write compressed output to '%s'\n", outFile);
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return 1;
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}
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if (!WriteFooter(fpOut, outFile, padCompressedBlock, resultLen, inSize, start)) return 1;
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free(outBuf);
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if (outFile != NULL) fclose(fpOut);
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free(buf);
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}
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