mirror of https://github.com/bsnes-emu/bsnes.git
92 lines
2.4 KiB
C++
92 lines
2.4 KiB
C++
//note: timings are completely unverified
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//due to the ST018 chip design (on-die ROM), testing is nearly impossible
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auto ArmDSP::busIdle() -> void {
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step(1);
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}
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auto ArmDSP::busRead(uint mode, uint32 addr) -> uint32 {
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step(1);
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static auto memory = [&](const uint8* memory, uint mode, uint32 addr) -> uint32 {
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if(mode & Word) {
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memory += addr & ~3;
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return memory[0] << 0 | memory[1] << 8 | memory[2] << 16 | memory[3] << 24;
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} else if(mode & Byte) {
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return memory[addr];
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} else {
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return 0; //should never occur
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}
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};
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switch(addr & 0xe000'0000) {
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case 0x0000'0000: return memory(programROM, mode, addr & 0x1ffff);
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case 0x2000'0000: return pipeline.fetch.instruction;
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case 0x4000'0000: break;
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case 0x6000'0000: return 0x40404001;
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case 0x8000'0000: return pipeline.fetch.instruction;
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case 0xa000'0000: return memory(dataROM, mode, addr & 0x7fff);
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case 0xc000'0000: return pipeline.fetch.instruction;
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case 0xe000'0000: return memory(programRAM, mode, addr & 0x3fff);
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}
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addr &= 0xe000'003f;
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if(addr == 0x4000'0010) {
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if(bridge.cputoarm.ready) {
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bridge.cputoarm.ready = false;
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return bridge.cputoarm.data;
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}
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}
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if(addr == 0x4000'0020) {
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return bridge.status();
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}
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return 0;
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}
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auto ArmDSP::busWrite(uint mode, uint32 addr, uint32 word) -> void {
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step(1);
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static auto memory = [](uint8* memory, uint mode, uint32 addr, uint32 word) {
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if(mode & Word) {
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memory += addr & ~3;
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*memory++ = word >> 0;
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*memory++ = word >> 8;
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*memory++ = word >> 16;
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*memory++ = word >> 24;
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} else if(mode & Byte) {
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memory += addr;
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*memory++ = word >> 0;
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}
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};
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switch(addr & 0xe000'0000) {
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case 0x0000'0000: return;
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case 0x2000'0000: return;
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case 0x4000'0000: break;
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case 0x6000'0000: return;
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case 0x8000'0000: return;
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case 0xa000'0000: return;
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case 0xc000'0000: return;
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case 0xe000'0000: return memory(programRAM, mode, addr & 0x3fff, word);
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}
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addr &= 0xe000'003f;
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word &= 0x0000'00ff;
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if(addr == 0x4000'0000) {
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bridge.armtocpu.ready = true;
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bridge.armtocpu.data = word;
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}
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if(addr == 0x4000'0010) bridge.signal = true;
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if(addr == 0x4000'0020) bridge.timerlatch.byte(0) = word;
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if(addr == 0x4000'0024) bridge.timerlatch.byte(1) = word;
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if(addr == 0x4000'0028) bridge.timerlatch.byte(2) = word;
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if(addr == 0x4000'002c) bridge.timer = bridge.timerlatch;
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}
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