mirror of https://github.com/bsnes-emu/bsnes.git
84 lines
1.9 KiB
C++
84 lines
1.9 KiB
C++
auto SPC7110::aluMultiply() -> void {
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addClocks(30);
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if(r482e & 1) {
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//signed 16-bit x 16-bit multiplication
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int16 r0 = (int16)(r4824 | r4825 << 8);
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int16 r1 = (int16)(r4820 | r4821 << 8);
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int result = r0 * r1;
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r4828 = result;
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r4829 = result >> 8;
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r482a = result >> 16;
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r482b = result >> 24;
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} else {
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//unsigned 16-bit x 16-bit multiplication
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uint16 r0 = (uint16)(r4824 | r4825 << 8);
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uint16 r1 = (uint16)(r4820 | r4821 << 8);
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uint result = r0 * r1;
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r4828 = result;
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r4829 = result >> 8;
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r482a = result >> 16;
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r482b = result >> 24;
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}
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r482f &= 0x7f;
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}
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auto SPC7110::aluDivide() -> void {
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addClocks(40);
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if(r482e & 1) {
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//signed 32-bit x 16-bit division
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int32 dividend = (int32)(r4820 | r4821 << 8 | r4822 << 16 | r4823 << 24);
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int16 divisor = (int16)(r4826 | r4827 << 8);
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int32 quotient;
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int16 remainder;
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if(divisor) {
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quotient = (int32)(dividend / divisor);
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remainder = (int32)(dividend % divisor);
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} else {
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//illegal division by zero
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quotient = 0;
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remainder = dividend;
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}
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r4828 = quotient;
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r4829 = quotient >> 8;
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r482a = quotient >> 16;
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r482b = quotient >> 24;
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r482c = remainder;
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r482d = remainder >> 8;
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} else {
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//unsigned 32-bit x 16-bit division
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uint32 dividend = (uint32)(r4820 | r4821 << 8 | r4822 << 16 | r4823 << 24);
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uint16 divisor = (uint16)(r4826 | r4827 << 8);
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uint32 quotient;
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uint16 remainder;
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if(divisor) {
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quotient = (uint32)(dividend / divisor);
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remainder = (uint16)(dividend % divisor);
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} else {
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//illegal division by zero
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quotient = 0;
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remainder = dividend;
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}
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r4828 = quotient;
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r4829 = quotient >> 8;
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r482a = quotient >> 16;
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r482b = quotient >> 24;
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r482c = remainder;
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r482d = remainder >> 8;
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}
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r482f &= 0x7f;
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}
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