Moving a Statement into Local Variable

[ClarionCoder51]

I am attempting to put the prompt letter into a local variable. The only problem is, I need to know HOW to DEFINE a variable and HOW to move a text value, like 'A>', into it using it in a mov statement. Every single possible combination of syntax and code that I could come up with doesn't work, so I'm hoping someone will atleast throw out an innertube so I won't drown in code in my sleep.

[Troy Martin]

EDIT: reading over your previous topic, I've shaved some stuff off.

Write a callable function called, say, strcpy, that copies a null-terminated string byte-by-byte from a string pointed to by SI to an array of bytes (another string, hehe) in DI. Voila.

You can't move/copy strings with the MOV instruction.

[kop99]

You can use "movsX", "cmpsX" assembly command for string operations.

[qw]

You don't need a string if the prompt is just one letter.

Code: Select all

[section .data]
prompt_letter: db 0
[section .code]
mov byte [prompt_letter], 'A'

Maybe you'd better show us your code and tell us what assembler you are using (the above example is in NASM syntax).

[ClarionCoder51]

Ok. In order to add '>' I would just call a separate string, like

Code: Select all

[section .data]
prompt_letter: db 0
prompt_arrow: db '>'
[section .code]
mov byte [prompt_letter], 'A'
lea si, prompt_letter
call print_string   ; <--- That functon prints the string to vid memory
lea si, prompt_arrow
call print_string 

...assuming that [prompt_letter] doesn't do a char return and puts '>' on the next line, which it shouldn't.

[qw]

In NASM syntax, "lea si, prompt_arrow" should be "lea si, [prompt_arrow]" or a plain "mov si, prompt_arrow". And "print_string" should be printing a character, not a string.

Again, you'd better show us your code and tell us what assembler you are using.