mirror of
https://github.com/dborth/vbagx.git
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85 lines
3.0 KiB
C++
85 lines
3.0 KiB
C++
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/* goombarom.c - functions to find uncompressed Game Boy ROM images
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stored within a larger file (e.g. Goomba Color ROMs, TAR archives)
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Copyright (C) 2014 libertyernie
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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When compiling in Visual Studio, set all goombarom files to compile
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as C++ code (Properties -> C/C++ -> Advanced -> Compile As.)
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*/
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#include <stdlib.h>
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#include <string.h>
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#include "goombarom.h"
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const char NINTENDO_LOGO_GB[48] = { 0xCE, 0xED, 0x66, 0x66, 0xCC, 0x0D, 0x00, 0x0B, 0x03, 0x73, 0x00, 0x83, 0x00, 0x0C, 0x00, 0x0D, 0x00, 0x08, 0x11, 0x1F, 0x88, 0x89, 0x00, 0x0E, 0xDC, 0xCC, 0x6E, 0xE6, 0xDD, 0xDD, 0xD9, 0x99, 0xBB, 0xBB, 0x67, 0x63, 0x6E, 0x0E, 0xEC, 0xCC, 0xDD, 0xDC, 0x99, 0x9F, 0xBB, 0xB9, 0x33, 0x3E };
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char gb_title_buffer[16];
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/* Finds the (expected) size of a Game Boy ROM, given a pointer to the start
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of the ROM image. */
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unsigned int gb_rom_size(const void* rom_start) {
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const char* ptr = (const char*)rom_start;
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return 0x8000 << ptr[0x148];
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}
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/* Finds the first Game Boy ROM in the given data block by looking for the
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Nintendo logo that shows when you turn the Game Boy on. If no valid data is
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found, this method will return NULL. */
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const void* gb_first_rom(const void* data, size_t length) {
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const char* ptr = (const char*)data;
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const char* end = ptr + length;
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int logo_pos = 0;
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while (ptr < end) {
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if (*ptr == NINTENDO_LOGO_GB[logo_pos]) {
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// match
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logo_pos++;
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if (logo_pos == 48) { // matched all of GB logo - on last byte (0x133)
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return ptr - 0x133;
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}
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} else {
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// no match, try again
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if (logo_pos > 0) {
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ptr -= logo_pos;
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logo_pos = 0;
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}
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}
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ptr++;
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}
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return NULL;
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}
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/* Returns a pointer to the next Game Boy ROM in the data. If no valid Game
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Boy ROM is found between *data and *data+length, starting at *rom, this method
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will return NULL.*/
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const void* gb_next_rom(const void* data, size_t length, const void* rom) {
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size_t diff = (const char*)rom - (const char*)data;
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if (diff > length) {
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//fprintf(stderr, "*data and *rom are farther apart than length param\n");
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return NULL;
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}
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size_t effective_length = length - diff;
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if (effective_length <= 0x200) {
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return NULL;
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}
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return gb_first_rom((const char*)rom + 0x134, effective_length - 0x134);
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}
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const char* gb_get_title(const void* rom, char* buffer) {
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char* title = buffer != NULL ? buffer : gb_title_buffer;
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title[15] = '\0';
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memcpy(title, (char*)rom + 0x134, 15);
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return title;
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}
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