39 lines
586 B
NASM
39 lines
586 B
NASM
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extern libz_strlen
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global libz_tolower
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section .text
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libz_tolower:
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sub rsp, 8 ;enter
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mov r11, rdi
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call libz_strlen
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mov r10, rax
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xor rcx, rcx ;we do this to clear rcx incase it had garbage in it before
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_loop:
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;do loop things
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mov r9, r11
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add r9, rcx
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mov r8b, [r9] ;this block here makes sure that our character is a capital letter and if its not a capital letter do nothing and return
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cmp r8b, 90
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ja _endloop
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cmp r8b, 65
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jb _endloop
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add r8b, 32 ;make the letter capital
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mov [r9], r8b
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_endloop:
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;end loop
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inc rcx
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cmp rcx, r10
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jle _loop
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add rsp, 8 ;exit
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ret
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