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comparison system.c @ 1117:928a65750345

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Initial support for Genesis/Megadrive PBC mode. VDP still needs Mode 4 to be useful.
author Michael Pavone <pavone@retrodev.com>
date Thu, 22 Dec 2016 19:51:25 -0800
parents 2eb54e24914e
children 4490c9c12272
comparison
equal deleted inserted replaced
1116:fe8c79f82c22 1117:928a65750345
1 #include <string.h> 1 #include <string.h>
2 #include "system.h" 2 #include "system.h"
3 #include "genesis.h" 3 #include "genesis.h"
4 #include "sms.h"
5
6 uint8_t safe_cmp(char *str, long offset, uint8_t *buffer, long filesize)
7 {
8 long len = strlen(str);
9 return filesize >= offset+len && !memcmp(str, buffer + offset, len);
10 }
4 11
5 system_type detect_system_type(uint8_t *rom, long filesize) 12 system_type detect_system_type(uint8_t *rom, long filesize)
6 { 13 {
7 if (filesize >= 0x104 && !memcmp("SEGA", rom + 0x100, 4)) { 14 if (safe_cmp("SEGA", 0x100, rom, filesize)) {
8 //TODO: Differentiate between vanilla Genesis and Sega CD/32X games 15 //TODO: Differentiate between vanilla Genesis and Sega CD/32X games
9 return SYSTEM_GENESIS; 16 return SYSTEM_GENESIS;
10 } 17 }
11 //TODO: Detect SMS and Jaguar ROMs here 18 if (safe_cmp("TMR SEGA", 0x1FF0, rom, filesize)
19 || safe_cmp("TMR SEGA", 0x3FF0, rom, filesize)
20 || safe_cmp("TMR SEGA", 0x7FF0, rom, filesize)
21 ) {
22 return SYSTEM_SMS;
23 }
24 //TODO: Detect Jaguar ROMs here
12 25
13 //More certain checks failed, look for a valid 68K reset vector 26 //More certain checks failed, look for a valid 68K reset vector
14 if (filesize >= 8) { 27 if (filesize >= 8) {
15 uint32_t reset = rom[4] << 24 | rom[5] << 16 | rom[6] << 8 | rom[7]; 28 uint32_t reset = rom[4] << 24 | rom[5] << 16 | rom[6] << 8 | rom[7];
16 if (!(reset & 1) && reset < filesize) { 29 if (!(reset & 1) && reset < filesize) {
25 { 38 {
26 switch (stype) 39 switch (stype)
27 { 40 {
28 case SYSTEM_GENESIS: 41 case SYSTEM_GENESIS:
29 return &(alloc_config_genesis(rom, rom_size, lock_on, lock_on_size, opts, force_region, info_out))->header; 42 return &(alloc_config_genesis(rom, rom_size, lock_on, lock_on_size, opts, force_region, info_out))->header;
43 #ifndef NO_Z80
44 case SYSTEM_SMS:
45 return &(alloc_configure_sms(rom, rom_size, lock_on, lock_on_size, opts, force_region, info_out))->header;
46 #endif
30 default: 47 default:
31 return NULL; 48 return NULL;
32 } 49 }
33 } 50 }