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| author | Kartik K. Agaram <vc@akkartik.com> | 2017-10-14 23:33:27 -0700 |
|---|---|---|
| committer | Kartik K. Agaram <vc@akkartik.com> | 2017-10-14 23:35:00 -0700 |
| commit | 311297cb006201f4706704b32c762630806c7adb (patch) | |
| tree | eacf64f46008fd48caf898d583a8bdac986b0baf /subx | |
| parent | c67ca4b92674620f3cae3b9301471e0321a7936c (diff) | |
| download | mu-311297cb006201f4706704b32c762630806c7adb.tar.gz | |
4066
I spent a while spelunking into the code generated by C compilers before realizing that ignoring the order of arguments for 'cmp' instructions clarifies everything.
Diffstat (limited to 'subx')
| -rw-r--r-- | subx/011direct_addressing.cc | 2 | ||||
| -rw-r--r-- | subx/012indirect_addressing.cc | 2 |
2 files changed, 2 insertions, 2 deletions
diff --git a/subx/011direct_addressing.cc b/subx/011direct_addressing.cc index facc8378..a12b5541 100644 --- a/subx/011direct_addressing.cc +++ b/subx/011direct_addressing.cc @@ -161,7 +161,7 @@ case 0xf7: { // xor r32 with r/m32 +run: SF=0; ZF=0; OF=0 :(before "End Single-Byte Opcodes") -case 0x39: { // compare r32 with r/m32 +case 0x39: { // set SF if r/m32 < r32 uint8_t modrm = next(); uint8_t reg2 = (modrm>>3)&0x7; trace(2, "run") << "compare reg " << NUM(reg2) << " with effective address" << end(); diff --git a/subx/012indirect_addressing.cc b/subx/012indirect_addressing.cc index 38c3d234..546df707 100644 --- a/subx/012indirect_addressing.cc +++ b/subx/012indirect_addressing.cc @@ -238,7 +238,7 @@ case 0x33: { // xor r/m32 with r32 +run: SF=0; ZF=0; OF=0 :(before "End Single-Byte Opcodes") -case 0x3b: { // compare r/m32 with r32 +case 0x3b: { // set SF if r32 < r/m32 uint8_t modrm = next(); uint8_t reg1 = (modrm>>3)&0x7; trace(2, "run") << "compare effective address with reg " << NUM(reg1) << end(); |