Mercurial > repos > blastem
diff vdp.c @ 1318:bfdd450e7dea
Initial work on handling the 128KB VRAM mode bit and some basic prep work for VDP test register support
author | Michael Pavone <pavone@retrodev.com> |
---|---|
date | Sun, 16 Apr 2017 16:40:04 -0700 |
parents | 810ae0287d66 |
children | b6796d63977f |
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--- a/vdp.c Sun Apr 16 16:38:56 2017 -0700 +++ b/vdp.c Sun Apr 16 16:40:04 2017 -0700 @@ -757,9 +757,15 @@ } } -void write_vram_byte(vdp_context *context, uint16_t address, uint8_t value) +void write_vram_byte(vdp_context *context, uint32_t address, uint8_t value) { if (context->regs[REG_MODE_2] & BIT_MODE_5) { + if (context->regs[REG_MODE_2] & BIT_128K_VRAM) { + address = (address & 0x3FC) | (address >> 1 & 0xFC01) | (address >> 9 & 0x2); + address ^= 1; + } else { + address &= 0xFFFF; + } if (!(address & 4)) { uint16_t sat_address = (context->regs[REG_SAT] & 0x7F) << 9; if(address >= sat_address && address < (sat_address + SAT_CACHE_SIZE*2)) { @@ -789,7 +795,8 @@ switch (start->cd & 0xF) { case VRAM_WRITE: - if (start->partial) { + //TODO: Support actually having 128K VRAM as an option + if (start->partial || (context->regs[REG_MODE_2] & BIT_128K_VRAM)) { //printf("VRAM Write: %X to %X at %d (line %d, slot %d)\n", start->value, start->address ^ 1, context->cycles, context->cycles/MCLKS_LINE, (context->cycles%MCLKS_LINE)/16); write_vram_byte(context, start->address ^ 1, start->partial == 2 ? start->value >> 8 : start->value); } else { @@ -865,6 +872,7 @@ //Should this happen after the prefetch or after the read? increment_address(context); } else { + //TODO: 128K VRAM Mode context->prefetch = context->vdpmem[context->address & 0xFFFE] << 8; context->flags2 |= FLAG2_READ_PENDING; } @@ -2456,7 +2464,7 @@ return -1; } if (context->flags & FLAG_PENDING) { - context->address = (context->address & 0x3FFF) | (value << 14); + context->address = (context->address & 0x3FFF) | (value << 14 & 0x1C000); //It seems like the DMA enable bit doesn't so much enable DMA so much //as it enables changing CD5 from control port writes uint8_t preserve = (context->regs[REG_MODE_2] & BIT_DMA_ENABLE) ? 0x3 : 0x23; @@ -2623,7 +2631,7 @@ void vdp_test_port_write(vdp_context * context, uint16_t value) { - //TODO: implement test register + context->test_port = value; } uint16_t vdp_control_port_read(vdp_context * context) @@ -2706,7 +2714,7 @@ uint16_t vdp_test_port_read(vdp_context * context) { //TODO: Find out what actually gets returned here - return 0xFFFF; + return context->test_port; } void vdp_adjust_cycles(vdp_context * context, uint32_t deduction)