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BMC-830425C-4391T: Update cpu banking

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- Fixes loading Mermaid game.
This commit is contained in:
retro-wertz
2019-06-23 20:15:32 +08:00
parent 706ee28294
commit 130580d70e
1 changed files with 16 additions and 36 deletions
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52
src/boards/bmc830425C4391t.c
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@@ -26,66 +26,46 @@
#include "mapinc.h"
static uint8 regs[2];
static uint8 isMermaid = 0;
static uint8 bank_size;
static uint8 inner_bank;
static uint8 outer_bank;
static SFORMAT StateRegs[] =
{
{ regs, 2, "REGS" },
{ &isMermaid, 1, "MERM" },
{ &inner_bank, 1, "INNB" },
{ &outer_bank, 1, "OUTB" },
{ &bank_size, 1, "SIZE" },
{ 0 }
};
static void Sync(void) {
uint8 bank_size = (regs[0] & 0x80) ? 0x07: 0x0F;
uint8 outer_bank = !isMermaid ? (regs[0] & 0x78) : 0x04;
uint8 inner_bank = regs[1];
uint8 game_block = regs[0] & 0x78;
/* TODO: Hacky and forced mapping of outer banks(game block)... */
if (!isMermaid) {
switch(game_block) {
case 0x00: /* botb outerbank=0 */
case 0x10: /* rocketeer outerbank=1 */
case 0x20: /* contra outerbank=2 */
case 0x28: /* ducktales outerbank=3 */
case 0x38: /* school fight outerbank=5 */
outer_bank = (game_block >> 4) + ((game_block & 0x08) ? 0x01 : 0x00);
outer_bank |= (game_block >> 3) & 1;
break;
case 0x30:
/* Mermaid game block is tricky (to me at least). Aim here is
* when this register is selected, ignore any other outer bank reg changes */
isMermaid = 1;
outer_bank = 0x04;
break;
}
}
setprg16r(outer_bank, 0x8000, (inner_bank & bank_size));
setprg16r(outer_bank, 0xC000, bank_size);
setchr8(0);
}
static DECLFW(M320Write) {
if ((A & 0xF0E0) == 0xF0E0) {
regs[0] = (A & 0x1F) << 3;
const uint8 chip[] = { 0, 0, 1, 0, 2, 3, 4, 5 };
/* address mask is inconsistent with that is in the wiki. Mask should be
* 0xFFE0 or Mermaid game will not work. */
if ((A & 0xFFE0) == 0xF0E0) {
outer_bank = chip[(A & 0x0F)];
bank_size = (A & 0x10) ? 0x07 : 0x0F;
}
regs[1] = V & 0x0F;
inner_bank = (V & 0x0F);
Sync();
}
static void M320Power(void) {
regs[0] = regs[1] = 0;
isMermaid = 0;
bank_size = 0x0F;
Sync();
SetReadHandler(0x8000, 0xFFFF, CartBR);
SetWriteHandler(0x8000, 0xFFFF, M320Write);
}
static void M320Reset(void) {
regs[0] = regs[1] = 0;
isMermaid = 0;
inner_bank = outer_bank = 0;
bank_size = 0x0F;
Sync();
}