+ 1

Assembly language

Please how can you interchange the second digit with the third digit in a four digit number in assembly language?

25th Dec 2022, 1:08 AM
Belonwu Chidumebi
Belonwu Chidumebi - avatar
4 Answers
+ 3
Create a file, mycode.asm, test it by assemble, link and run the exe files nasm -f win32 mycode.asm: ; Load data, 1234 in the EAX register mov eax, 1234 ; Extract the second and third digits mov ebx, eax ; copy the number to EBX and ebx, 0xF00 ; mask to isolate the third digit shr ebx, 8 ; shift the third digit into the lower bits and eax, 0xF0 ; mask to isolate the second digit shr eax, 4 ; shift the second digit into the lower bits ; Exchange the values of the second and third digits xor eax, ebx ; XOR the second and third digits ; Mask the original number to clear the second and third digits and ecx, eax ; copy the number to ECX not ecx ; invert the bits of ECX and ecx, 0xFFF0 ; mask to clear the second and third digits or ecx, eax ; OR the modified second and third digits into the original number ; ECX now contains the four-digit number with the exchanged second and third digits
25th Dec 2022, 3:46 AM
CalviŐ˛
CalviŐ˛ - avatar
+ 2
I am not very well versed in assembly, but I have learned that looking at others code can help in the learning process. If you can solve it using C you can put your C code into www.godbolt.org and look at a possible solution in assembly. Here is a way in C: https://code.sololearn.com/cqSPW6JUyk3t/?ref=app
25th Dec 2022, 2:19 AM
William Owens
William Owens - avatar
25th Dec 2022, 4:56 AM
CalviŐ˛
CalviŐ˛ - avatar
0
Thank you , this will really help. Please will it be a similar format if you are changing the first two digits with the last two. Asin 7320 changes to 2073
25th Dec 2022, 10:32 AM
Belonwu Chidumebi
Belonwu Chidumebi - avatar