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| author | Kartik Agaram <vc@akkartik.com> | 2019-05-04 14:07:37 -0700 |
|---|---|---|
| committer | Kartik Agaram <vc@akkartik.com> | 2019-05-04 14:07:37 -0700 |
| commit | e450523829337ff46d71ca6bab289982de85eafc (patch) | |
| tree | 95dfd92d79e754a45c120d1bfa557d64762b08b1 /subx | |
| parent | 02b105fee40399410e6aa05ee33d4ee2cef8fd4d (diff) | |
| download | mu-e450523829337ff46d71ca6bab289982de85eafc.tar.gz | |
5138
Drop some redundant transfers between registers. The x86 instruction set can perform most operations on all available registers, and things are more comprehensible if each conceptual variable has a single location.
Diffstat (limited to 'subx')
| -rw-r--r-- | subx/074print-int-decimal.subx | 15 |
1 files changed, 4 insertions, 11 deletions
diff --git a/subx/074print-int-decimal.subx b/subx/074print-int-decimal.subx index 72c99495..064d8672 100644 --- a/subx/074print-int-decimal.subx +++ b/subx/074print-int-decimal.subx @@ -43,22 +43,18 @@ print-int32-decimal: # out : (address stream), n : int32 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 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/disp8 + 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: - # EBX = n - 8b/copy 3/mod/direct 0/rm32/EAX . . . 3/r32/EBX . . # EBX = EAX $print-int32-decimal:read-loop: - # EAX = EBX(n) - 89/copy 3/mod/direct 0/rm32/EAX . . . 3/r32/EBX . . # EAX = EBX - b9/copy-to-ECX 0xa/imm32 # EAX, EDX = EAX / 10, EAX % 10 99/sign-extend-EAX-into-EDX f7 7/subop/idiv 3/mod/direct 1/rm32/ECX . . . . . . # divide EDX:EAX by ECX, storing quotient in EAX and remainder in EDX @@ -66,15 +62,12 @@ $print-int32-decimal:read-loop: 81 0/subop/add 3/mod/direct 2/rm32/EDX . . . . . 0x30/imm32 # add to EDX # push EDX 52/push-EDX - # EBX = n / 10 - 89/copy 3/mod/direct 3/rm32/EBX . . . 0/r32/EAX . . # EBX = EAX # if (EAX == 0) break 3d/compare-EAX-and 0/imm32 7f/jump-if-greater $print-int32-decimal:read-loop/disp8 $print-int32-decimal:read-break: # if (negative?) push('-') - 8b/copy 3/mod/direct 7/rm32/EDI . . . 0/r32/EAX . . # EAX = EDX - 3d/compare-EAX-and 0/imm32 + 81 7/subop/compare 3/mod/direct 7/rm32/EDI . . . . . 0/imm32/false # compare EDI 74/jump-if-equal $print-int32-decimal:write/disp8 68/push 0x2d/imm32/- $print-int32-decimal:write: |