mirror of https://github.com/bsnes-emu/bsnes.git
140 lines
4.0 KiB
C++
Executable File
140 lines
4.0 KiB
C++
Executable File
#ifdef SA1_CPP
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//====================
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//direct data transfer
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//====================
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void SA1::dma_normal() {
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while(mmio.dtc--) {
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uint8 data = regs.mdr;
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uint32 dsa = mmio.dsa++;
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uint32 dda = mmio.dda++;
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//source and destination cannot be the same
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if(mmio.sd == DMA::SourceBWRAM && mmio.dd == DMA::DestBWRAM) continue;
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if(mmio.sd == DMA::SourceIRAM && mmio.dd == DMA::DestIRAM ) continue;
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switch(mmio.sd) {
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case DMA::SourceROM: {
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if((dsa & 0x408000) == 0x008000 || (dsa & 0xc00000) == 0xc00000) {
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data = sa1bus.read(dsa);
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}
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} break;
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case DMA::SourceBWRAM: {
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if((dsa & 0x40e000) == 0x006000 || (dsa & 0xf00000) == 0x400000) {
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data = sa1bus.read(dsa);
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}
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} break;
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case DMA::SourceIRAM: {
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data = memory::iram.read(dsa & 0x07ff);
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} break;
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}
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switch(mmio.dd) {
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case DMA::DestBWRAM: {
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if((dda & 0x40e000) == 0x006000 || (dda & 0xf00000) == 0x400000) {
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sa1bus.write(dda, data);
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}
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} break;
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case DMA::DestIRAM: {
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memory::iram.write(dda & 0x07ff, data);
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} break;
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}
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}
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mmio.dma_irqfl = true;
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if(mmio.dma_irqen) mmio.dma_irqcl = 0;
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}
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//((byte & 6) << 3) + (byte & 1) explanation:
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//transforms a byte index (0-7) into a planar index:
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//result[] = { 0, 1, 16, 17, 32, 33, 48, 49 };
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//works for 2bpp, 4bpp and 8bpp modes
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//===========================
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//type-1 character conversion
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//===========================
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void SA1::dma_cc1() {
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memory::cc1bwram.dma = true;
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mmio.chdma_irqfl = true;
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if(mmio.chdma_irqen) {
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mmio.chdma_irqcl = 0;
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cpu.regs.irq = 1;
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}
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}
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uint8 SA1::dma_cc1_read(unsigned addr) {
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//16 bytes/char (2bpp); 32 bytes/char (4bpp); 64 bytes/char (8bpp)
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unsigned charmask = (1 << (6 - mmio.dmacb)) - 1;
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if((addr & charmask) == 0) {
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//buffer next character to I-RAM
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unsigned bpp = 2 << (2 - mmio.dmacb);
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unsigned bpl = (8 << mmio.dmasize) >> mmio.dmacb;
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unsigned bwmask = memory::cartram.size() - 1;
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unsigned tile = ((addr - mmio.dsa) & bwmask) >> (6 - mmio.dmacb);
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unsigned ty = (tile >> mmio.dmasize);
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unsigned tx = tile & ((1 << mmio.dmasize) - 1);
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unsigned bwaddr = mmio.dsa + ty * 8 * bpl + tx * bpp;
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for(unsigned y = 0; y < 8; y++) {
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uint64 data = 0;
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for(unsigned byte = 0; byte < bpp; byte++) {
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data |= (uint64)memory::cartram.read((bwaddr + byte) & bwmask) << (byte << 3);
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}
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bwaddr += bpl;
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uint8 out[] = { 0, 0, 0, 0, 0, 0, 0, 0 };
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for(unsigned x = 0; x < 8; x++) {
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out[0] |= (data & 1) << (7 - x); data >>= 1;
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out[1] |= (data & 1) << (7 - x); data >>= 1;
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if(mmio.dmacb == 2) continue;
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out[2] |= (data & 1) << (7 - x); data >>= 1;
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out[3] |= (data & 1) << (7 - x); data >>= 1;
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if(mmio.dmacb == 1) continue;
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out[4] |= (data & 1) << (7 - x); data >>= 1;
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out[5] |= (data & 1) << (7 - x); data >>= 1;
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out[6] |= (data & 1) << (7 - x); data >>= 1;
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out[7] |= (data & 1) << (7 - x); data >>= 1;
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}
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for(unsigned byte = 0; byte < bpp; byte++) {
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unsigned p = mmio.dda + (y << 1) + ((byte & 6) << 3) + (byte & 1);
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memory::iram.write(p & 0x07ff, out[byte]);
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}
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}
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}
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return memory::iram.read((mmio.dda + (addr & charmask)) & 0x07ff);
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}
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//===========================
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//type-2 character conversion
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//===========================
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void SA1::dma_cc2() {
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//select register file index (0-7 or 8-15)
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const uint8 *brf = &mmio.brf[(dma.line & 1) << 3];
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unsigned bpp = 2 << (2 - mmio.dmacb);
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unsigned addr = mmio.dda & 0x07ff;
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addr &= ~((1 << (7 - mmio.dmacb)) - 1);
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addr += (dma.line & 8) * bpp;
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addr += (dma.line & 7) * 2;
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for(unsigned byte = 0; byte < bpp; byte++) {
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uint8 output = 0;
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for(unsigned bit = 0; bit < 8; bit++) {
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output |= ((brf[bit] >> byte) & 1) << (7 - bit);
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}
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memory::iram.write(addr + ((byte & 6) << 3) + (byte & 1), output);
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}
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dma.line = (dma.line + 1) & 15;
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}
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#endif
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