Mercurial > repos > blastem
changeset 672:18ef3b61e70b
Restore emulation of Z80 being locked out of the 68K bus during DMA and the like
| author | Michael Pavone <pavone@retrodev.com> |
|---|---|
| date | Sat, 03 Jan 2015 20:20:15 -0800 |
| parents | 8ad39a2b0bce |
| children | 7f1b5570b2a1 |
| files | blastem.c |
| diffstat | 1 files changed, 11 insertions(+), 4 deletions(-) [+] |
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--- a/blastem.c Sat Jan 03 20:13:51 2015 -0800 +++ b/blastem.c Sat Jan 03 20:20:15 2015 -0800 @@ -666,12 +666,15 @@ uint8_t z80_read_bank(uint32_t location, void * vcontext) { z80_context * context = vcontext; + genesis_context *gen = context->system; + if (gen->bus_busy) { + context->current_cycle = context->sync_cycle; + } //typical delay from bus arbitration context->current_cycle += 3 * MCLKS_PER_Z80; + //TODO: add cycle for an access right after a previous one location &= 0x7FFF; - //TODO: add cycle for an access right after a previous one - //TODO: block Z80 if VDP has the bus or the 68K is blocked on a VDP access if (context->mem_pointers[1]) { return context->mem_pointers[1][location ^ 1]; } @@ -687,11 +690,15 @@ void *z80_write_bank(uint32_t location, void * vcontext, uint8_t value) { z80_context * context = vcontext; + genesis_context *gen = context->system; + if (gen->bus_busy) { + context->current_cycle = context->sync_cycle; + } //typical delay from bus arbitration context->current_cycle += 3 * MCLKS_PER_Z80; + //TODO: add cycle for an access right after a previous one + location &= 0x7FFF; - //TODO: add cycle for an access right after a previous one - //TODO: block Z80 if VDP has the bus or the 68K is blocked on a VDP access uint32_t address = context->bank_reg << 15 | location; if (address >= 0xE00000) { address &= 0xFFFF;