diff options
Diffstat (limited to 'blastem.c')
| -rw-r--r-- | blastem.c | 11 |
1 files changed, 7 insertions, 4 deletions
@@ -144,6 +144,11 @@ uint16_t read_dma_value(uint32_t address) return 0; } +uint16_t get_open_bus_value() +{ + return read_dma_value(genesis->m68k->last_prefetch_address/2); +} + void adjust_int_cycle(m68k_context * context, vdp_context * v_context) { //static int old_int_cycle = CYCLE_NEVER; @@ -705,8 +710,7 @@ uint8_t io_read(uint32_t location, m68k_context * context) } else { if (location == 0x1100) { value = z80_enabled ? !z80_get_busack(gen->z80, context->current_cycle) : !gen->z80->busack; - //TODO: actual pre-fetch emulation - value |= 0x4E; + value |= (get_open_bus_value() >> 8) & 0xFE; dprintf("Byte read of BUSREQ returned %d @ %d (reset: %d)\n", value, context->current_cycle, gen->z80->reset); } else if (location == 0x1200) { value = !gen->z80->reset; @@ -726,8 +730,7 @@ uint16_t io_read_w(uint32_t location, m68k_context * context) value = value | (value << 8); } else { value <<= 8; - //TODO: actual pre-fetch emulation - value |= 0x73; + value |= get_open_bus_value() & 0xFF; } return value; } |