mirror of https://github.com/bsnes-emu/bsnes.git
73 lines
1.5 KiB
C++
73 lines
1.5 KiB
C++
#include <gba/gba.hpp>
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namespace GameBoyAdvance {
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Bus bus;
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auto IO::readIO(uint mode, uint32 addr) -> uint32 {
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uint32 word = 0;
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if(mode & Word) {
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addr &= ~3;
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word |= readIO(addr + 0) << 0;
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word |= readIO(addr + 1) << 8;
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word |= readIO(addr + 2) << 16;
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word |= readIO(addr + 3) << 24;
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} else if(mode & Half) {
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addr &= ~1;
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word |= readIO(addr + 0) << 0;
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word |= readIO(addr + 1) << 8;
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} else if(mode & Byte) {
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word |= readIO(addr + 0) << 0;
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}
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return word;
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}
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auto IO::writeIO(uint mode, uint32 addr, uint32 word) -> void {
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if(mode & Word) {
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addr &= ~3;
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writeIO(addr + 0, word >> 0);
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writeIO(addr + 1, word >> 8);
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writeIO(addr + 2, word >> 16);
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writeIO(addr + 3, word >> 24);
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} else if(mode & Half) {
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addr &= ~1;
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writeIO(addr + 0, word >> 0);
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writeIO(addr + 1, word >> 8);
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} else if(mode & Byte) {
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writeIO(addr + 0, word >> 0);
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}
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}
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struct UnmappedIO : IO {
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auto readIO(uint32 addr) -> uint8 override { return 0; }
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auto writeIO(uint32 addr, uint8 byte) -> void override {}
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};
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static UnmappedIO unmappedIO;
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auto Bus::mirror(uint32 addr, uint32 size) -> uint32 {
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uint32 base = 0;
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if(size) {
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uint32 mask = 1 << 27; //28-bit bus
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while(addr >= size) {
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while(!(addr & mask)) mask >>= 1;
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addr -= mask;
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if(size > mask) {
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size -= mask;
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base += mask;
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}
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mask >>= 1;
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}
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base += addr;
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}
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return base;
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}
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auto Bus::power() -> void {
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for(auto n : range(0x400)) io[n] = &unmappedIO;
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}
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}
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