mirror of https://github.com/pret/pokecrystal.git
93 lines
3.2 KiB
C
93 lines
3.2 KiB
C
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#include "proto.h"
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struct command * get_commands_from_file (const unsigned char * data, unsigned short * restrict size, unsigned short * restrict slack) {
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struct command * result = malloc(*size * sizeof(struct command));
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unsigned short remaining = *size;
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struct command * current = result;
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const unsigned char * rp = data;
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while (1) {
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if (!(remaining --)) goto error;
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current -> command = *rp >> 5;
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current -> count = *(rp ++) & 31;
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if (current -> command == 7) {
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current -> command = current -> count >> 2;
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current -> count = (current -> count & 3) << 8;
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if (current -> command == 7) {
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// long commands inside long commands are not allowed, but if the count is 0x300 here, it means that the original byte was 0xff
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if (current -> count == 0x300) break;
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goto error;
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}
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if (!(remaining --)) goto error;
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current -> count |= *(rp ++);
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}
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current -> count ++;
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switch (current -> command) {
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case 0:
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if (remaining <= current -> count) goto error;
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current -> value = rp - data;
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rp += current -> count;
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remaining -= current -> count;
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case 3:
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break;
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case 1: case 2: {
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unsigned char p;
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if (remaining <= current -> command) goto error;
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current -> value = 0;
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for (p = 0; p < current -> command; p ++) current -> value |= *(rp ++) << (p << 3);
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remaining -= current -> command;
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} break;
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default:
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if (!(remaining --)) goto error;
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if ((current -> value = *(rp ++)) & 128)
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current -> value = 127 - current -> value;
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else {
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if (!(remaining --)) goto error;
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current -> value = (current -> value << 8) | *(rp ++);
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}
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}
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current ++;
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}
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if (slack) *slack = *size - (rp - data);
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*size = current - result;
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return realloc(result, *size * sizeof(struct command));
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error:
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free(result);
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return NULL;
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}
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unsigned char * get_uncompressed_data (const struct command * commands, const unsigned char * compressed, unsigned short * size) {
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const struct command * limit = commands + *size;
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unsigned char * result = malloc(MAX_FILE_SIZE + MAX_COMMAND_COUNT);
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unsigned char * current = result;
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unsigned short p;
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for (; commands < limit; commands ++) {
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switch (commands -> command) {
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case 0:
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memcpy(current, compressed + commands -> value, commands -> count);
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current += commands -> count;
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break;
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case 1: case 2:
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for (p = 0; p < commands -> count; p ++) *(current ++) = commands -> value >> ((p % commands -> command) << 3);
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break;
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case 3:
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memset(current, 0, commands -> count);
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current += commands -> count;
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break;
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default: {
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const unsigned char * ref = ((commands -> value < 0) ? current : result) + commands -> value;
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for (p = 0; p < commands -> count; p ++) {
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current[p] = ref[(commands -> command == 6) ? -(int) p : p];
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if (commands -> command == 5) current[p] = bit_flipping_table[current[p]];
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}
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current += commands -> count;
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}
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}
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if ((current - result) > MAX_FILE_SIZE) {
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free(result);
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return NULL;
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}
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}
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*size = current - result;
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return result;
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}
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