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Need a small core change, too
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,166 @@ | ||
| /* | ||
| This file is part of MiST-firmware | ||
| MiST-firmware is free software; you can redistribute it and/or modify | ||
| it under the terms of the GNU General Public License as published by | ||
| the Free Software Foundation; either version 3 of the License, or | ||
| (at your option) any later version. | ||
| MiST-firmware is distributed in the hope that it will be useful, | ||
| but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
| GNU General Public License for more details. | ||
| You should have received a copy of the GNU General Public License | ||
| along with this program. If not, see <http://www.gnu.org/licenses/>. | ||
| */ | ||
|
|
||
| #include <stdint.h> | ||
| #include <stdio.h> | ||
| #include "snes.h" | ||
| #include "fat_compat.h" | ||
| #include "debug.h" | ||
|
|
||
| enum HeaderField { | ||
| CartName = 0x00, | ||
| Mapper = 0x15, | ||
| RomType = 0x16, | ||
| RomSize = 0x17, | ||
| RamSize = 0x18, | ||
| CartRegion = 0x19, | ||
| Company = 0x1a, | ||
| Version = 0x1b, | ||
| Complement = 0x1c, //inverse checksum | ||
| Checksum = 0x1e, | ||
| ResetVector = 0x3c, | ||
| }; | ||
|
|
||
| // From Main_MiSTer/support/snes/snes.cpp | ||
| static uint32_t score_header(FIL *file, uint32_t offset, uint32_t addr) | ||
| { | ||
| int score = 0; | ||
| UINT br; | ||
| uint8_t *data = sector_buffer; | ||
|
|
||
| snes_debugf("Header address: %08x offset: %d", addr, offset); | ||
|
|
||
| if ((f_lseek(file, offset + addr) != FR_OK) || | ||
| (f_tell(file) != (offset + addr)) || | ||
| (f_read(file, data, 64, &br) != FR_OK)) { | ||
| return 0; | ||
| } | ||
|
|
||
| uint16_t resetvector = data[ResetVector] | (data[ResetVector + 1] << 8); | ||
| uint16_t checksum = data[Checksum] | (data[Checksum + 1] << 8); | ||
| uint16_t complement = data[Complement] | (data[Complement + 1] << 8); | ||
|
|
||
| snes_debugf("Reset vector: %04x, checksum: %04x, complement: %04x", resetvector, checksum, complement); | ||
|
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||
| //$00:[0000-7fff] contains uninitialized RAM and MMIO. | ||
| //reset vector must point to ROM at $00:[8000-ffff] to be considered valid. | ||
| if (resetvector < 0x8000) return 0; | ||
|
|
||
| uint8_t resetop = 0; | ||
| if (f_lseek(file, ((addr & ~0x7fff) | (resetvector & 0x7fff)) + offset ) != FR_OK) return 0; | ||
| if (f_read(file, &resetop, 1, &br) != FR_OK) return 0; | ||
| //uint8_t resetop = data[(addr & ~0x7fff) | (resetvector & 0x7fff)]; //first opcode executed upon reset | ||
| uint8_t mapper = data[Mapper] & ~0x10; //mask off irrelevent FastROM-capable bit | ||
|
|
||
| //some images duplicate the header in multiple locations, and others have completely | ||
| //invalid header information that cannot be relied upon. | ||
| //below code will analyze the first opcode executed at the specified reset vector to | ||
| //determine the probability that this is the correct header. | ||
|
|
||
| //most likely opcodes | ||
| if (resetop == 0x78 //sei | ||
| || resetop == 0x18 //clc (clc; xce) | ||
| || resetop == 0x38 //sec (sec; xce) | ||
| || resetop == 0x9c //stz $nnnn (stz $4200) | ||
| || resetop == 0x4c //jmp $nnnn | ||
| || resetop == 0x5c //jml $nnnnnn | ||
| ) score += 8; | ||
|
|
||
| //plausible opcodes | ||
| if (resetop == 0xc2 //rep #$nn | ||
| || resetop == 0xe2 //sep #$nn | ||
| || resetop == 0xad //lda $nnnn | ||
| || resetop == 0xae //ldx $nnnn | ||
| || resetop == 0xac //ldy $nnnn | ||
| || resetop == 0xaf //lda $nnnnnn | ||
| || resetop == 0xa9 //lda #$nn | ||
| || resetop == 0xa2 //ldx #$nn | ||
| || resetop == 0xa0 //ldy #$nn | ||
| || resetop == 0x20 //jsr $nnnn | ||
| || resetop == 0x22 //jsl $nnnnnn | ||
| ) score += 4; | ||
|
|
||
| //implausible opcodes | ||
| if (resetop == 0x40 //rti | ||
| || resetop == 0x60 //rts | ||
| || resetop == 0x6b //rtl | ||
| || resetop == 0xcd //cmp $nnnn | ||
| || resetop == 0xec //cpx $nnnn | ||
| || resetop == 0xcc //cpy $nnnn | ||
| ) score -= 4; | ||
|
|
||
| //least likely opcodes | ||
| if (resetop == 0x00 //brk #$nn | ||
| || resetop == 0x02 //cop #$nn | ||
| || resetop == 0xdb //stp | ||
| || resetop == 0x42 //wdm | ||
| || resetop == 0xff //sbc $nnnnnn,x | ||
| ) score -= 8; | ||
|
|
||
| //at times, both the header and reset vector's first opcode will match ... | ||
| //fallback and rely on info validity in these cases to determine more likely header. | ||
|
|
||
| //a valid checksum is the biggest indicator of a valid header. | ||
| if ((checksum + complement) == 0xffff && (checksum != 0) && (complement != 0)) score += 4; | ||
|
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||
|
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||
| if (addr == 0x007fc0 && mapper == 0x20) score += 2; //0x20 is usually LoROM | ||
| if (addr == 0x00ffc0 && mapper == 0x21) score += 2; //0x21 is usually HiROM | ||
| if (addr == 0x007fc0 && mapper == 0x22) score += 2; //0x22 is usually SDD1 | ||
| if (addr == 0x40ffc0 && mapper == 0x25) score += 2; //0x25 is usually ExHiROM | ||
|
|
||
| if (data[Company] == 0x33) score += 2; //0x33 indicates extended header | ||
| if (data[RomType] < 0x08) score++; | ||
| if (data[RomSize] < 0x10) score++; | ||
| if (data[RamSize] < 0x08) score++; | ||
| if (data[CartRegion] < 14) score++; | ||
|
|
||
| snes_debugf("Resetop: %02x mapper: %02x score: %d", | ||
| resetop, mapper, score); | ||
|
|
||
| if (score < 0) score = 0; | ||
| return score; | ||
| } | ||
|
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||
| char snes_getromtype(FIL *file) | ||
| { | ||
| uint32_t score_lo, score_hi, score_ex; | ||
| UINT br; | ||
| FSIZE_t size = f_size(file); | ||
| FSIZE_t offset = size & 0x1ff; | ||
|
|
||
| score_lo = score_header(file, offset, (FSIZE_t) 0x007fc0); | ||
| score_hi = score_header(file, offset, (FSIZE_t) 0x00ffc0); | ||
| score_ex = score_header(file, offset, (FSIZE_t) 0x40ffc0); | ||
| f_rewind(file); | ||
|
|
||
| if (score_ex) score_ex += 4; //favor ExHiROM on images > 32mbits | ||
| if (score_lo >= score_hi && score_lo >= score_ex) { | ||
| iprintf("Detected LoROM\n"); | ||
| return 0; // probably LoROM | ||
| } | ||
| if (score_hi >= score_ex) { | ||
| iprintf("Detected HiROM\n"); | ||
| return 1; // probably HiROM | ||
| } | ||
| if (score_ex) { | ||
| iprintf("Detected ExHiROM\n"); | ||
| return 2; // probably ExHiROM | ||
| } | ||
| iprintf("No clue about ROM type\n"); | ||
| return 0; // no idea, fall back to LoROM | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,25 @@ | ||
| /* | ||
| This file is part of MiST-firmware | ||
| MiST-firmware is free software; you can redistribute it and/or modify | ||
| it under the terms of the GNU General Public License as published by | ||
| the Free Software Foundation; either version 3 of the License, or | ||
| (at your option) any later version. | ||
| MiST-firmware is distributed in the hope that it will be useful, | ||
| but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
| GNU General Public License for more details. | ||
| You should have received a copy of the GNU General Public License | ||
| along with this program. If not, see <http://www.gnu.org/licenses/>. | ||
| */ | ||
|
|
||
| #ifndef SNES_H | ||
| #define SNES_H | ||
|
|
||
| #include "FatFs/ff.h" | ||
|
|
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| char snes_getromtype(FIL *file); | ||
|
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| #endif // SNES_H |