Programming Forums - View Single Post - How do i convert this code into assembly ??

lostcauz · Feb 1st, 2005, 6:40 AM

I simply looked at your C code and wrote it in assembler. I offered some other code by a more experienced assembler programmer for comparison also. While compiler output is a good way to learn and see a conversion the goal, for me at least, is to write tighter, faster code than the compiler. Either way it's awesome to see some others interested in learning the language. I commented the code I wrote.

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; assumes eax contains 'a' variable and ecx contains 'b' variable

begin:  cmp eax, ecx   ; compare the 2 variables
        je  getout     ; if equal, we are done
        ja  higher     ; if a is greater than b jump to higher
        sub ecx, eax   ; otherwise a<b so subtract a from b
        jmp begin      ; loop until equal
higher: sub eax, ecx   ; subtract b from a
        jmp begin      ; loop
getout:                ; result returned in eax

Feb 1st, 2005, 6:40 AM	#7
lostcauz Hobbyist Programmer Join Date: Nov 2004 Location: 1691 miles East of L.A. Posts: 159 Rep Power: 4	I simply looked at your C code and wrote it in assembler. I offered some other code by a more experienced assembler programmer for comparison also. While compiler output is a good way to learn and see a conversion the goal, for me at least, is to write tighter, faster code than the compiler. Either way it's awesome to see some others interested in learning the language. I commented the code I wrote. (Toggle Plain Text) ; assumes eax contains 'a' variable and ecx contains 'b' variable begin: cmp eax, ecx ; compare the 2 variables je getout ; if equal, we are done ja higher ; if a is greater than b jump to higher sub ecx, eax ; otherwise a<b so subtract a from b jmp begin ; loop until equal higher: sub eax, ecx ; subtract b from a jmp begin ; loop getout: ; result returned in eax ; assumes eax contains 'a' variable and ecx contains 'b' variable begin: cmp eax, ecx ; compare the 2 variables je getout ; if equal, we are done ja higher ; if a is greater than b jump to higher sub ecx, eax ; otherwise a<b so subtract a from b jmp begin ; loop until equal higher: sub eax, ecx ; subtract b from a jmp begin ; loop getout: ; result returned in eax __________________ -- lostcauz Stepped in what?... Behind whose barn?... I didn't even know they had a cow!