mirror of https://github.com/bsnes-emu/bsnes.git
97 lines
3.5 KiB
C++
97 lines
3.5 KiB
C++
auto ARM7TDMI::ADD(uint32 source, uint32 modify, bool carry, bool updateFlags) -> uint32 {
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uint32 result = source + modify + carry;
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if(updateFlags) {
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uint32 overflow = ~(source ^ modify) & (source ^ result);
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cpsr().v = 1 << 31 & (overflow);
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cpsr().c = 1 << 31 & (overflow ^ source ^ modify ^ result);
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cpsr().z = result == 0;
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cpsr().n = result.bit(31);
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}
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return result;
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}
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auto ARM7TDMI::ASR(uint32 source, uint8 shift) -> uint32 {
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carry = cpsr().c;
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if(shift == 0) return source;
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carry = shift > 32 ? source & 1 << 31 : source & 1 << shift - 1;
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source = shift > 31 ? (int32)source >> 31 : (int32)source >> shift;
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return source;
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}
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auto ARM7TDMI::BIT(uint32 result, bool updateFlags) -> uint32 {
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if(updateFlags) {
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cpsr().c = carry;
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cpsr().z = result == 0;
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cpsr().n = result.bit(31);
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}
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return result;
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}
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auto ARM7TDMI::LSL(uint32 source, uint8 shift) -> uint32 {
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carry = cpsr().c;
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if(shift == 0) return source;
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carry = shift > 32 ? 0 : source & 1 << 32 - shift;
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source = shift > 31 ? 0 : source << shift;
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return source;
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}
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auto ARM7TDMI::LSR(uint32 source, uint8 shift) -> uint32 {
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carry = cpsr().c;
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if(shift == 0) return source;
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carry = shift > 32 ? 0 : source & 1 << shift - 1;
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source = shift > 31 ? 0 : source >> shift;
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return source;
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}
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auto ARM7TDMI::MUL(uint32 product, uint32 multiplicand, uint32 multiplier, bool updateFlags) -> uint32 {
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idle();
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if(multiplier >> 8 && multiplier >> 8 != 0xffffff) idle();
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if(multiplier >> 16 && multiplier >> 16 != 0xffff) idle();
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if(multiplier >> 24 && multiplier >> 24 != 0xff) idle();
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product += multiplicand * multiplier;
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if(updateFlags) {
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cpsr().z = product == 0;
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cpsr().n = product.bit(31);
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}
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return product;
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}
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auto ARM7TDMI::ROR(uint32 source, uint8 shift) -> uint32 {
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carry = cpsr().c;
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if(shift == 0) return source;
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if(shift &= 31) source = source << 32 - shift | source >> shift;
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carry = source & 1 << 31;
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return source;
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}
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auto ARM7TDMI::RRX(uint32 source) -> uint32 {
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carry = source.bit(0);
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return cpsr().c << 31 | source >> 1;
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}
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auto ARM7TDMI::SUB(uint32 source, uint32 modify, bool carry, bool updateFlags) -> uint32 {
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return ADD(source, ~modify, carry, updateFlags);
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}
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auto ARM7TDMI::TST(uint4 mode) -> bool {
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switch(mode) {
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case 0: return cpsr().z == 1; //EQ (equal)
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case 1: return cpsr().z == 0; //NE (not equal)
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case 2: return cpsr().c == 1; //CS (carry set)
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case 3: return cpsr().c == 0; //CC (carry clear)
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case 4: return cpsr().n == 1; //MI (negative)
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case 5: return cpsr().n == 0; //PL (positive)
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case 6: return cpsr().v == 1; //VS (overflow)
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case 7: return cpsr().v == 0; //VC (no overflow)
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case 8: return cpsr().c == 1 && cpsr().z == 0; //HI (unsigned higher)
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case 9: return cpsr().c == 0 || cpsr().z == 1; //LS (unsigned lower or same)
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case 10: return cpsr().n == cpsr().v; //GE (signed greater than or equal)
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case 11: return cpsr().n != cpsr().v; //LT (signed less than)
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case 12: return cpsr().z == 0 && cpsr().n == cpsr().v; //GT (signed greater than)
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case 13: return cpsr().z == 1 || cpsr().n != cpsr().v; //LE (signed less than or equal)
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case 14: return true; //AL (always)
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case 15: return false; //NV (never)
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}
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unreachable;
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}
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