some advice

From: psi (i_at_m.t)
Date: 06/28/04 

Date: Mon, 28 Jun 2004 09:19:01 GMT

I now have to translate simple routines of bignum from C to assembly.
I would like to hear some advice on errors and eventually speed up the
minor() routine.

Thank you
/*--------------------------------------*/
typedef struct{
   unsigned len;
   unsigned *num;
}num;

this is the routine (that compare bignum) to traslate in assembly

static int minoa(const num* a, const num* b)
{unsigned *aa, *bb;
 if(a->len < b->len) R 1;
 if(a->len > b->len) R -1;
 aa=a->num, bb=b->num;
 F(aa+=a->len-1, bb+=a->len-1; *aa == *bb; --aa, --bb)
              if( a->num == aa) R 0;
 R *bb > *aa ? 1: -1;
}

this is my traslation
    
section _TEXT public align=1 class=CODE use32
    
    global _minor_s
    
; offset della struttura num_s */
%define len_off 0
%define num_off 4
    
    
; int a minor(&num1, &num2) */
_minor:
    push ebp
    mov ebp, esp
    push ebx
    push esi
    push edi
    push edx
;------------------*/
    mov esi, [ebp+8]
    mov edi, [ebp+12]
    mov eax, [esi]
    mov ebx, [edi]
    cmp eax, ebx
    jae .con ; b == <; a < b*/
    mov eax, 1
    jmp short .fine
.con:
    jbe .con1
    mov eax, -1
    jmp short .fine
.con1:
    dec ebx ; len - 1 */
    dec eax
    mov esi, [esi + num_off]
    mov edi, [edi + num_off]
    push esi
    shl eax, 2 ; a=4*a b=4*b */
    shl ebx, 2
    add esi, eax
    add edi, ebx
    pop eax
    mov edx, 4
.lo:
    mov ebx, [esi]
    cmp ebx, [edi]
    jne .esci
    cmp esi, eax
    jne .co
    mov eax, 0
    jmp short .fine
.co:
    sub esi, edx
    sub edi, edx
    jmp short .lo
.esci:
    jbe .con2
    mov eax, -1
    jmp short .fine
.con2:
    mov eax, 1
.fine:
    pop edx
    pop edi
    pop esi
    pop ebx
    mov esp, ebp
    pop ebp
    ret
    
/*----------------------------*/
/*or in 'my' macro assembly */

section _TEXT public align=1 class=CODE use32

global _minor_s

/* offset della struttura num_s */
%define len_off 0
%define num_off 4

/* int a minor(&num1, &num2) */
_minor:
{< k | k=s;
 < b, i, j, r
/*------------------*/
 i = [k+8]; j = [k+12]
 a = [i]; b = [j]
 a <> b
    jae .con /* b == <; a < b*/
         { a = 1; jmp short .fine }
  .con:
    jbe .con1
         { a = -1; jmp short .fine }
.con1:
   --b; --a /* len - 1 */
   i = [i + num_off]; j = [j + num_off]
   < i;
     a <<= 2; b <<=2 /* a=4*a b=4*b */
     i += a ; j += b
> a;
   r=4;
.lo:
      b = [i]
      b!=[j] ? .esci;
      i==a ! .co;
        { a=0; jmp short .fine }
     .co:
      i -= r | j -= r
      jmp short .lo
.esci:
   jbe .con2
     { a=-1; jmp short .fine }
.con2:
  a=1
.fine:
> b, i, j, r
 s=k | > k
 ret
}

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