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| author | Kartik Agaram <vc@akkartik.com> | 2019-05-04 14:17:13 -0700 |
|---|---|---|
| committer | Kartik Agaram <vc@akkartik.com> | 2019-05-04 14:17:13 -0700 |
| commit | d2410e14c6af85f917f79de6f19fb6e60d37d74f (patch) | |
| tree | e29596ead3ef839c6365a1405e288e1d1d38a819 /subx/074print-int-decimal.subx | |
| parent | e450523829337ff46d71ca6bab289982de85eafc (diff) | |
| download | mu-d2410e14c6af85f917f79de6f19fb6e60d37d74f.tar.gz | |
5139
Replace the 'negative?' variable with a second read from the stack. It's not clear if this is more or less efficient (https://github.com/akkartik/mu/pull/20#issuecomment-489285130) but taking out the local variable does seem easier to read.
Diffstat (limited to 'subx/074print-int-decimal.subx')
| -rw-r--r-- | subx/074print-int-decimal.subx | 16 |
1 files changed, 6 insertions, 10 deletions
diff --git a/subx/074print-int-decimal.subx b/subx/074print-int-decimal.subx index 064d8672..a3e2eb9e 100644 --- a/subx/074print-int-decimal.subx +++ b/subx/074print-int-decimal.subx @@ -16,14 +16,14 @@ print-int32-decimal: # out : (address stream), n : int32 # pseudocode: # push sentinel - # EAX, negative? = abs(n), sign(n) + # EAX = abs(n) # while true # sign-extend EAX into EDX # EAX, EDX = EAX/10, EAX%10 # EDX += '0' # push EDX # if (EAX == 0) break - # if negative? + # if n < 0 # push '-' # while true # pop into EAX @@ -42,18 +42,15 @@ print-int32-decimal: # out : (address stream), n : int32 51/push-ECX 52/push-EDX 53/push-EBX - 57/push-EDI # ten/ECX = 10 b9/copy-to-ECX 0xa/imm32 # push sentinel 68/push 0/imm32/sentinel - # EAX, negative?/EDI = abs(n), sign(n) - bf/copy-to-EDI 0/imm32/false + # EAX = abs(n) 8b/copy 1/mod/*+disp8 5/rm32/EBP . . . 0/r32/EAX 0xc/disp8 . # EAX = *(EBP+12) 3d/compare-EAX-with 0/imm32 7d/jump-if-greater-or-equal $print-int32-decimal:read-loop/disp8 f7 3/subop/negate 3/mod/direct 0/rm32/EAX . . . . . . # negate EAX - bf/copy-to-EDI 1/imm32/true $print-int32-decimal:read-loop: # EAX, EDX = EAX / 10, EAX % 10 99/sign-extend-EAX-into-EDX @@ -66,9 +63,9 @@ $print-int32-decimal:read-loop: 3d/compare-EAX-and 0/imm32 7f/jump-if-greater $print-int32-decimal:read-loop/disp8 $print-int32-decimal:read-break: - # if (negative?) push('-') - 81 7/subop/compare 3/mod/direct 7/rm32/EDI . . . . . 0/imm32/false # compare EDI - 74/jump-if-equal $print-int32-decimal:write/disp8 + # if (n < 0) push('-') + 81 7/subop/compare 1/mod/*+disp8 5/rm32/EBP . . . . 0xc/disp8 0/imm32 # compare *(EBP+12) + 7d/jump-if-greater-or-equal $print-int32-decimal:write/disp8 68/push 0x2d/imm32/- $print-int32-decimal:write: # EBX = out @@ -91,7 +88,6 @@ $print-int32-decimal:write-loop: eb/jump $print-int32-decimal:write-loop/disp8 $print-int32-decimal:end: # . restore registers - 57/pop-to-EDI 5b/pop-to-EBX 5a/pop-to-EDX 59/pop-to-ECX |