GCC NASM 混合編程， 這一次有點實用性， 借用程序堆棧實現了數制ascii轉換

GCC NASM 混合編程， 這一次大概有點實用性了， 是借用程序堆棧實現了數制ascii轉換，當然負數的部分沒寫，留個思考額餘地吧

;testnasm.asm
global _bin2ascii, _mystack

extern _s

[BITS 32]

section .data

_tab: db '0123456789abcdef', 0

section .text
	
_bin2ascii: ; char bin2ascii(int i);
	push ebp
	mov ebp, esp
	push ebx
	
	mov ebx, _tab
	mov eax, [3 * 4 + esp]
	xlat

	pop ebx
	pop ebp
	ret
	
_mystack: ; int mystack(int i);
	push ebp
	mov ebp, esp
	push ebx
	push ecx
	push edx
	
	xor ecx, ecx
	mov eax, [5 * 4 + esp]
	mov ebx, 16

.1:
	or eax, eax
	jz .2
	xor edx, edx
	div ebx
	push edx
	inc ecx
	jmp .1
.2:

	mov eax, ecx
	mov ebx, _s
.3:
	pop dword[ebx]
	add ebx, 4
	loop .3
	
	pop edx
	pop ecx
	pop ebx
	pop ebp
	ret
	
	

// testc_nasm.c
#include <stdio.h>

char bin2ascii(int i);
int mystack(int i);
int s[0xff];

void mybin2ascii(char* str, int i) {
	int l, j;
	if(i < 0) {
		i = -i;
	}
	if(i == 0){
		s[0] = '0';
		s[1] = '\0';
		return;
	} else {
		l = mystack(i);
		for(j = 0; j < l; j++) {
			str[j] = bin2ascii(s[j]);
		}
		str[j] = '\0';
	}
}

int main(void) {

	int i = 65535, l;

	char str[0xff];
	mybin2ascii(str, i);
	printf("%d = 0x%s\n", i, str);
	
	i = 65537;
	mybin2ascii(str, i);
	printf("%d = 0x%s\n", i, str);

}