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UserspaceEmulator: Make SBB actually respect the SoftCPU carry flag
We were forgetting to set the host CPU's carry flag before executing the SBB instruction. This made the result a bit unpredictable. :^)
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a9f92e5d75
commit
6230c60296
1 changed files with 15 additions and 2 deletions
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@ -343,12 +343,17 @@ static T op_sub(SoftCPU& cpu, const T& dest, const T& src)
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return result;
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}
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template<typename T>
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static T op_sbb(SoftCPU& cpu, const T& dest, const T& src)
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template<typename T, bool cf>
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static T op_sbb_impl(SoftCPU& cpu, const T& dest, const T& src)
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{
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T result = 0;
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u32 new_flags = 0;
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if constexpr (cf)
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asm volatile("stc");
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else
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asm volatile("clc");
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if constexpr (sizeof(T) == 4) {
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asm volatile("sbbl %%ecx, %%eax\n"
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: "=a"(result)
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@ -374,6 +379,14 @@ static T op_sbb(SoftCPU& cpu, const T& dest, const T& src)
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return result;
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}
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template<typename T>
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static T op_sbb(SoftCPU& cpu, T& dest, const T& src)
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{
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if (cpu.cf())
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return op_sbb_impl<T, true>(cpu, dest, src);
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return op_sbb_impl<T, false>(cpu, dest, src);
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}
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template<typename T>
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static T op_add(SoftCPU& cpu, T& dest, const T& src)
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{
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