Mercurial > repos > blastem
changeset 473:1358045c0bdd
Implement undocumented 8-bit VRAM read
| author | Mike Pavone <pavone@retrodev.com> |
|---|---|
| date | Sun, 15 Sep 2013 23:00:17 -0700 |
| parents | 93dc0382fd70 |
| children | e128e55710bd |
| files | vdp.c |
| diffstat | 1 files changed, 20 insertions(+), 6 deletions(-) [+] |
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--- a/vdp.c Sun Sep 15 22:43:01 2013 -0700 +++ b/vdp.c Sun Sep 15 23:00:17 2013 -0700 @@ -378,12 +378,22 @@ context->colors[addr + CRAM_SIZE*2] = color_map[(value & 0xEEE) | FBUF_HILIGHT]; } -#define VRAM_READ 0 -#define VRAM_WRITE 1 -#define CRAM_READ 8 -#define CRAM_WRITE 3 -#define VSRAM_READ 4 -#define VSRAM_WRITE 5 +#define VRAM_READ 0 //0000 +#define VRAM_WRITE 1 //0001 +//2 would trigger register write 0010 +#define CRAM_WRITE 3 //0011 +#define VSRAM_READ 4 //0100 +#define VSRAM_WRITE 5//0101 +//6 would trigger regsiter write 0110 +//7 is a mystery +#define CRAM_READ 8 //1000 +//9 is also a mystery //1001 +//A would trigger register write 1010 +//B is a mystery 1011 +#define VRAM_READ8 0xC //1100 +//D is a mystery 1101 +//E would trigger register write 1110 +//F is a mystery 1111 #define DMA_START 0x20 void external_slot(vdp_context * context) @@ -1591,6 +1601,10 @@ } value |= context->vdpmem[context->address | 1]; break; + case VRAM_READ8: + value = context->vdpmem[context->address ^ 1]; + value |= context->fifo[context->fifo_write].value & 0xFF00; + break; case CRAM_READ: value = context->cram[(context->address/2) & (CRAM_SIZE-1)] & CRAM_BITS; value |= context->fifo[context->fifo_write].value & ~CRAM_BITS;