58 lines
1.2 KiB
Plaintext
58 lines
1.2 KiB
Plaintext
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# Fill a region of memory with zeroes.
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== code
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copy-bytes: # src: (addr byte), dest: (addr byte), size: int
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# pseudocode:
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# curr-src/esi = src
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# curr-dest/edi = dest
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# i/ecx = 0
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# while true
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# if (i >= size) break
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# *curr-dest = *curr-src
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# ++curr-src
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# ++curr-dest
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# ++i
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#
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# . prologue
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55/push-ebp
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89/<- %ebp 4/r32/esp
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# . save registers
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50/push-eax
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51/push-ecx
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52/push-edx
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56/push-esi
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57/push-edi
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# curr-src/esi = src
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8b/-> *(ebp+8) 6/r32/esi
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# curr-dest/edi = dest
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8b/-> *(ebp+0xc) 7/r32/edi
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# var i/ecx: int = 0
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b9/copy-to-ecx 0/imm32
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# edx = size
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8b/-> *(ebp+0x10) 2/r32/edx
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{
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# if (i >= size) break
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39/compare %ecx 2/r32/edx
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7d/jump-if->= break/disp8
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# *curr-dest = *curr-src
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8a/byte-> *esi 0/r32/AL
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88/byte<- *edi 0/r32/AL
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# update
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46/increment-esi
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47/increment-edi
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41/increment-ecx
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eb/jump loop/disp8
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}
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$copy-bytes:end:
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# . restore registers
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5f/pop-to-edi
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5e/pop-to-esi
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5a/pop-to-edx
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59/pop-to-ecx
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58/pop-to-eax
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# . epilogue
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89/<- %esp 5/r32/ebp
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5d/pop-to-ebp
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c3/return
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