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flag tests for opcode 2b

This commit is contained in:
Kartik Agaram 2019-05-13 10:00:44 -07:00
parent 32a8e12efa
commit 97ef7c4362
1 changed files with 69 additions and 7 deletions
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76
subx/014indirect_addressing.cc
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@ -188,21 +188,83 @@ case 0x2b: { // subtract r/m32 from r32
const uint8_t arg1 = (modrm>>3)&0x7;
trace(Callstack_depth+1, "run") << "subtract r/m32 from " << rname(arg1) << end();
const int32_t* signed_arg2 = effective_address(modrm);
int64_t signed_full_result = Reg[arg1].i - *signed_arg2;
Reg[arg1].i -= *signed_arg2;
trace(Callstack_depth+1, "run") << "storing 0x" << HEXWORD << Reg[arg1].i << end();
SF = (Reg[arg1].i < 0);
ZF = (Reg[arg1].i == 0);
OF = (Reg[arg1].i != signed_full_result);
const int32_t signed_result = Reg[arg1].i - *signed_arg2;
int64_t signed_full_result = static_cast<int64_t>(Reg[arg1].i) - *signed_arg2;
SF = (signed_result < 0);
ZF = (signed_result == 0);
OF = (signed_result != signed_full_result);
// set CF
uint32_t unsigned_arg2 = static_cast<uint32_t>(*signed_arg2);
uint32_t unsigned_result = Reg[arg1].u - unsigned_arg2;
uint64_t unsigned_full_result = Reg[arg1].u - unsigned_arg2;
uint64_t unsigned_full_result = static_cast<uint64_t>(Reg[arg1].u) - unsigned_arg2;
CF = (unsigned_result != unsigned_full_result);
trace(Callstack_depth+1, "run") << "SF=" << SF << "; ZF=" << ZF << "; CF=" << CF << "; OF=" << OF << end();
Reg[arg1].i = signed_result;
trace(Callstack_depth+1, "run") << "storing 0x" << HEXWORD << Reg[arg1].i << end();
break;
}
:(code)
void test_subtract_mem_at_r32_from_r32_signed_overflow() {
Reg[EAX].i = 0x2000;
Reg[EBX].i = 0x80000000; // smallest negative signed integer
run(
"== 0x1\n" // code segment
// op ModR/M SIB displacement immediate
" 2b 18 \n" // subtract *EAX from EBX
// ModR/M in binary: 11 (direct mode) 011 (src EBX) 000 (dest EAX)
"== 0x2000\n" // data segment
"ff ff ff 7f\n" // largest positive signed integer
);
CHECK_TRACE_CONTENTS(
"run: subtract r/m32 from EBX\n"
"run: effective address is 0x00002000 (EAX)\n"
"run: effective address contains 7fffffff\n"
"run: SF=0; ZF=0; CF=0; OF=1\n"
"run: storing 0x00000001\n"
);
}
void test_subtract_mem_at_r32_from_r32_unsigned_overflow() {
Reg[EAX].i = 0x2000;
Reg[EBX].i = 0;
run(
"== 0x1\n" // code segment
// op ModR/M SIB displacement immediate
" 2b 18 \n" // subtract *EAX from EBX
// ModR/M in binary: 11 (direct mode) 011 (src EBX) 000 (dest EAX)
"== 0x2000\n" // data segment
"01 00 00 00\n" // 1
);
CHECK_TRACE_CONTENTS(
"run: subtract r/m32 from EBX\n"
"run: effective address is 0x00002000 (EAX)\n"
"run: effective address contains 1\n"
"run: SF=1; ZF=0; CF=1; OF=0\n"
"run: storing 0xffffffff\n"
);
}
void test_subtract_mem_at_r32_from_r32_signed_and_unsigned_overflow() {
Reg[EAX].i = 0x2000;
Reg[EBX].i = 0;
run(
"== 0x1\n" // code segment
// op ModR/M SIB displacement immediate
" 2b 18 \n" // subtract *EAX from EBX
// ModR/M in binary: 11 (direct mode) 011 (src EBX) 000 (dest EAX)
"== 0x2000\n" // data segment
"00 00 00 80\n" // smallest negative signed integer
);
CHECK_TRACE_CONTENTS(
"run: subtract r/m32 from EBX\n"
"run: effective address is 0x00002000 (EAX)\n"
"run: effective address contains 80000000\n"
"run: SF=1; ZF=0; CF=1; OF=1\n"
"run: storing 0x80000000\n"
);
}
//:: and
:(code)
void test_and_r32_with_mem_at_r32() {