ShuriZma
/
visualboyadvance-m
mirror of https://github.com/visualboyadvance-m/visualboyadvance-m.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

GB: Support 4MiB MBC30 ROM bank select. 

MBC30 is a variant of MBC3 with a 4MiB ROM size and a larger RAM size.

https://gekkio.fi/files/gb-docs/gbctr.pdf

Allow addressing 4MiB of the ROM in MBC3 ROM bank select if the ROM size
is 4MiB.

Fix provided by roytam1.

- Fix #652.

Signed-off-by: Rafael Kitover <rkitover@gmail.com>
This commit is contained in:
Rafael Kitover 2020-04-24 20:57:51 +00:00
parent a972da8ddb
commit 045e95ab4e
1 changed files with 12 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
src/gb/gbMemory.cpp
View File

@ -361,8 +361,15 @@ void mapperMBC3ROM(uint16_t address, uint8_t value)
case 0x0000: // RAM enable register
gbDataMBC3.mapperRAMEnable = ((value & 0x0a) == 0x0a ? 1 : 0);
break;
case 0x2000: // ROM bank select
value = value & 0x7f;
case 0x2000: { // ROM bank select
// 4MiB, MBC30
bool mbc30 = gbRomSize == 0x00400000;
if (mbc30)
value = value & 0xff; // 4MiB
else
value = value & 0x7f; // 2MiB
if (value == 0)
value = 1;
if (value == gbDataMBC3.mapperROMBank)
@ -371,13 +378,16 @@ void mapperMBC3ROM(uint16_t address, uint8_t value)
tmpAddress = value << 14;
tmpAddress &= gbRomSizeMask;
gbDataMBC3.mapperROMBank = value;
gbMemoryMap[0x04] = &gbRom[tmpAddress];
gbMemoryMap[0x05] = &gbRom[tmpAddress + 0x1000];
gbMemoryMap[0x06] = &gbRom[tmpAddress + 0x2000];
gbMemoryMap[0x07] = &gbRom[tmpAddress + 0x3000];
break;
}
case 0x4000: // RAM bank select
if (value < 8) {
if (value == gbDataMBC3.mapperRAMBank)