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bsnes/higan/sfc/alt/ppu-balanced/render/addsub.cpp

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Update to 20100808 release. byuu says: This fixes libsnes and debugger builds, and collapses bsnes/ppu/bppu to bsnes/ppu and bsnes/dsp/sdsp to bsnes/dsp. It also introduces bsnes/sync.sh, which will synchronize all of asnes/ with bsnes/, excepting the custom speed-focused modules. So far, that's bsnes/ppu (scanline renderer) and bsnes/dsp (state machine.) Should make keeping the two ports in sync much, much easier. It's basically the same thing as before, only you run sync.sh and have a few duplicated folders now. May make it clearer by creating a stub/ or src/ folder inside bsnes to do all of the copying, so that you only see the custom folders in bsnes/' root directory.
2010-08-09 13:31:09 +00:00
#ifdef PPU_CPP
First version split into asnes and bsnes.
2010-08-09 13:28:56 +00:00
//color addition / subtraction
//thanks go to blargg for the optimized algorithms
Update to 20100808 release. byuu says: This fixes libsnes and debugger builds, and collapses bsnes/ppu/bppu to bsnes/ppu and bsnes/dsp/sdsp to bsnes/dsp. It also introduces bsnes/sync.sh, which will synchronize all of asnes/ with bsnes/, excepting the custom speed-focused modules. So far, that's bsnes/ppu (scanline renderer) and bsnes/dsp (state machine.) Should make keeping the two ports in sync much, much easier. It's basically the same thing as before, only you run sync.sh and have a few duplicated folders now. May make it clearer by creating a stub/ or src/ folder inside bsnes to do all of the copying, so that you only see the custom folders in bsnes/' root directory.
2010-08-09 13:31:09 +00:00
inline uint16 PPU::addsub(uint32 x, uint32 y, bool halve) {
First version split into asnes and bsnes.
2010-08-09 13:28:56 +00:00
if(!regs.color_mode) {
if(!halve) {
unsigned sum = x + y;
unsigned carry = (sum - ((x ^ y) & 0x0421)) & 0x8420;
return (sum - carry) | (carry - (carry >> 5));
} else {
return (x + y - ((x ^ y) & 0x0421)) >> 1;
}
} else {
unsigned diff = x - y + 0x8420;
unsigned borrow = (diff - ((x ^ y) & 0x8420)) & 0x8420;
if(!halve) {
return (diff - borrow) & (borrow - (borrow >> 5));
} else {
return (((diff - borrow) & (borrow - (borrow >> 5))) & 0x7bde) >> 1;
}
}
}
#endif