crypto/bn/bn_mul.c:822: error: INTEGER_OVERFLOW_L2
  ([0, max(4294967295, `*r`)] - [0, max(4294967295, `*r`)]):unsigned32 by call to `bn_mul_recursive`.
Showing all 15 steps of the trace


crypto/bn/bn_mul.c:760:1: Parameter `*r`
758.    * t needs to be n2*3
759.    */
760. > void bn_mul_high(BN_ULONG *r, BN_ULONG *a, BN_ULONG *b, BN_ULONG *l, int n2,
761.   	     BN_ULONG *t)
762.   	{

crypto/bn/bn_mul.c:822:3: Call
820.   # endif
821.   		{
822.   		bn_mul_recursive(&(t[0]),&(r[0]),&(r[n]),n,0,0,&(t[n2]));
         ^
823.   		bn_mul_recursive(r,&(a[n]),&(b[n]),n,0,0,&(t[n2]));
824.   		}

crypto/bn/bn_mul.c:393:1: Parameter `*a`
  391.    */
  392.   /* dnX may not be positive, but n2/2+dnX has to be */
  393. > void bn_mul_recursive(BN_ULONG *r, BN_ULONG *a, BN_ULONG *b, size_t n2,
  394.   		      int dna, int dnb, BN_ULONG *t)
  395.   	{

crypto/bn/bn_mul.c:431:5: Call
  429.   		}
  430.   	/* r=(a[0]-a[1])*(b[1]-b[0]) */
  431.   	c1=bn_cmp_part_words(a,&(a[n]),tna,n-tna);
             ^
  432.   	c2=bn_cmp_part_words(&(b[n]),b,tnb,tnb-n);
  433.   	zero=neg=0;

crypto/bn/bn_lib.c:822:1: Parameter `*b`
    820.      All lengths are the number of BN_ULONGs...  */
    821.   
    822. > int bn_cmp_part_words(const BN_ULONG *a, const BN_ULONG *b,
    823.   	int cl, int dl)
    824.   	{

crypto/bn/bn_mul.c:437:3: Call
  435.   		{
  436.   	case -4:
  437.   		bn_sub_part_words(t,      &(a[n]),a,      tna,tna-n); /* - */
           ^
  438.   		bn_sub_part_words(&(t[n]),b,      &(b[n]),tnb,n-tnb); /* - */
  439.   		break;

crypto/bn/bn_mul.c:80:1: Parameter `*b`
    78.      assembler counterparts for the systems that use assembler files.  */
    79.   
    80. > BN_ULONG bn_sub_part_words(BN_ULONG *r,
    81.   			   const BN_ULONG *a, const BN_ULONG *b,
    82.   			   size_t cl, ssize_t dl)

crypto/bn/bn_mul.c:87:6: Call
    85.   
    86.   	assert(cl >= 0);
    87.   	c = bn_sub_words(r, a, b, cl);
               ^
    88.   
    89.   	if (dl == 0)

crypto/bn/bn_asm.c:393:1: <LHS trace>
391.   #endif /* !BN_LLONG */
392.   
393. > BN_ULONG bn_sub_words(BN_ULONG *r, const BN_ULONG *a, const BN_ULONG *b, size_t n)
394.           {
395.   	BN_ULONG t1,t2;

crypto/bn/bn_asm.c:393:1: Parameter `*a`
      391.   #endif /* !BN_LLONG */
      392.   
      393. > BN_ULONG bn_sub_words(BN_ULONG *r, const BN_ULONG *a, const BN_ULONG *b, size_t n)
      394.           {
      395.   	BN_ULONG t1,t2;

crypto/bn/bn_asm.c:404:3: Assignment
      402.   	while (n&~3)
      403.   		{
      404.   		t1=a[0]; t2=b[0];
               ^
      405.   		r[0]=(t1-t2-c)&BN_MASK2;
      406.   		if (t1 != t2) c=(t1 < t2);

crypto/bn/bn_asm.c:393:1: <RHS trace>
391.   #endif /* !BN_LLONG */
392.   
393. > BN_ULONG bn_sub_words(BN_ULONG *r, const BN_ULONG *a, const BN_ULONG *b, size_t n)
394.           {
395.   	BN_ULONG t1,t2;

crypto/bn/bn_asm.c:393:1: Parameter `*b`
      391.   #endif /* !BN_LLONG */
      392.   
      393. > BN_ULONG bn_sub_words(BN_ULONG *r, const BN_ULONG *a, const BN_ULONG *b, size_t n)
      394.           {
      395.   	BN_ULONG t1,t2;

crypto/bn/bn_asm.c:404:12: Assignment
      402.   	while (n&~3)
      403.   		{
      404.   		t1=a[0]; t2=b[0];
                        ^
      405.   		r[0]=(t1-t2-c)&BN_MASK2;
      406.   		if (t1 != t2) c=(t1 < t2);

crypto/bn/bn_asm.c:405:3: Binary operation: ([0, max(4294967295, *r)] - [0, max(4294967295, *r)]):unsigned32 by call to `bn_mul_recursive` 
      403.   		{
      404.   		t1=a[0]; t2=b[0];
      405.   		r[0]=(t1-t2-c)&BN_MASK2;
               ^
      406.   		if (t1 != t2) c=(t1 < t2);
      407.   		t1=a[1]; t2=b[1];

BN_ULONG bn_sub_words(BN_ULONG *r, const BN_ULONG *a, const BN_ULONG *b, size_t n)
        {
	BN_ULONG t1,t2;
	int c=0;
	assert(n >= 0);
	if (n <= 0) return((BN_ULONG)0);
#ifndef OPENSSL_SMALL_FOOTPRINT
	while (n&~3)
		{
		t1=a[0]; t2=b[0];
		r[0]=(t1-t2-c)&BN_MASK2;
		if (t1 != t2) c=(t1 < t2);
		t1=a[1]; t2=b[1];
		r[1]=(t1-t2-c)&BN_MASK2;
		if (t1 != t2) c=(t1 < t2);
		t1=a[2]; t2=b[2];
		r[2]=(t1-t2-c)&BN_MASK2;
		if (t1 != t2) c=(t1 < t2);
		t1=a[3]; t2=b[3];
		r[3]=(t1-t2-c)&BN_MASK2;
		if (t1 != t2) c=(t1 < t2);
		a+=4; b+=4; r+=4; n-=4;
		}
#endif
	while (n)
		{
		t1=a[0]; t2=b[0];
		r[0]=(t1-t2-c)&BN_MASK2;
		if (t1 != t2) c=(t1 < t2);
		a++; b++; r++; n--;
		}
	return(c);
	}
['void bn_mul_high(BN_ULONG *r, BN_ULONG *a, BN_ULONG *b, BN_ULONG *l, int n2,\n\t     BN_ULONG *t)\n\t{\n\tint i,n;\n\tint c1,c2;\n\tint neg,oneg,zero;\n\tBN_ULONG ll,lc,*lp,*mp;\n# ifdef BN_COUNT\n\tfprintf(stderr," bn_mul_high %d * %d\\n",n2,n2);\n# endif\n\tn=n2/2;\n\tneg=zero=0;\n\tc1=bn_cmp_words(&(a[0]),&(a[n]),n);\n\tc2=bn_cmp_words(&(b[n]),&(b[0]),n);\n\tswitch (c1*3+c2)\n\t\t{\n\tcase -4:\n\t\tbn_sub_words(&(r[0]),&(a[n]),&(a[0]),n);\n\t\tbn_sub_words(&(r[n]),&(b[0]),&(b[n]),n);\n\t\tbreak;\n\tcase -3:\n\t\tzero=1;\n\t\tbreak;\n\tcase -2:\n\t\tbn_sub_words(&(r[0]),&(a[n]),&(a[0]),n);\n\t\tbn_sub_words(&(r[n]),&(b[n]),&(b[0]),n);\n\t\tneg=1;\n\t\tbreak;\n\tcase -1:\n\tcase 0:\n\tcase 1:\n\t\tzero=1;\n\t\tbreak;\n\tcase 2:\n\t\tbn_sub_words(&(r[0]),&(a[0]),&(a[n]),n);\n\t\tbn_sub_words(&(r[n]),&(b[0]),&(b[n]),n);\n\t\tneg=1;\n\t\tbreak;\n\tcase 3:\n\t\tzero=1;\n\t\tbreak;\n\tcase 4:\n\t\tbn_sub_words(&(r[0]),&(a[0]),&(a[n]),n);\n\t\tbn_sub_words(&(r[n]),&(b[n]),&(b[0]),n);\n\t\tbreak;\n\t\t}\n\toneg=neg;\n# ifdef BN_MUL_COMBA\n\tif (n == 8)\n\t\t{\n\t\tbn_mul_comba8(&(t[0]),&(r[0]),&(r[n]));\n\t\tbn_mul_comba8(r,&(a[n]),&(b[n]));\n\t\t}\n\telse\n# endif\n\t\t{\n\t\tbn_mul_recursive(&(t[0]),&(r[0]),&(r[n]),n,0,0,&(t[n2]));\n\t\tbn_mul_recursive(r,&(a[n]),&(b[n]),n,0,0,&(t[n2]));\n\t\t}\n\tif (l != NULL)\n\t\t{\n\t\tlp= &(t[n2+n]);\n\t\tc1=(int)(bn_add_words(lp,&(r[0]),&(l[0]),n));\n\t\t}\n\telse\n\t\t{\n\t\tc1=0;\n\t\tlp= &(r[0]);\n\t\t}\n\tif (neg)\n\t\tneg=(int)(bn_sub_words(&(t[n2]),lp,&(t[0]),n));\n\telse\n\t\t{\n\t\tbn_add_words(&(t[n2]),lp,&(t[0]),n);\n\t\tneg=0;\n\t\t}\n\tif (l != NULL)\n\t\t{\n\t\tbn_sub_words(&(t[n2+n]),&(l[n]),&(t[n2]),n);\n\t\t}\n\telse\n\t\t{\n\t\tlp= &(t[n2+n]);\n\t\tmp= &(t[n2]);\n\t\tfor (i=0; i<n; i++)\n\t\t\tlp[i]=((~mp[i])+1)&BN_MASK2;\n\t\t}\n\tif (l != NULL)\n\t\t{\n\t\tlp= &(t[n2]);\n\t\tc1= (int)(bn_add_words(lp,&(t[n2+n]),&(l[0]),n));\n\t\t}\n\telse\n\t\t{\n\t\tlp= &(t[n2+n]);\n\t\tc1=0;\n\t\t}\n\tc1+=(int)(bn_add_words(&(t[n2]),lp,  &(r[0]),n));\n\tif (oneg)\n\t\tc1-=(int)(bn_sub_words(&(t[n2]),&(t[n2]),&(t[0]),n));\n\telse\n\t\tc1+=(int)(bn_add_words(&(t[n2]),&(t[n2]),&(t[0]),n));\n\tc2 =(int)(bn_add_words(&(r[0]),&(r[0]),&(t[n2+n]),n));\n\tc2+=(int)(bn_add_words(&(r[0]),&(r[0]),&(r[n]),n));\n\tif (oneg)\n\t\tc2-=(int)(bn_sub_words(&(r[0]),&(r[0]),&(t[n]),n));\n\telse\n\t\tc2+=(int)(bn_add_words(&(r[0]),&(r[0]),&(t[n]),n));\n\tif (c1 != 0)\n\t\t{\n\t\ti=0;\n\t\tif (c1 > 0)\n\t\t\t{\n\t\t\tlc=c1;\n\t\t\tdo\t{\n\t\t\t\tll=(r[i]+lc)&BN_MASK2;\n\t\t\t\tr[i++]=ll;\n\t\t\t\tlc=(lc > ll);\n\t\t\t\t} while (lc);\n\t\t\t}\n\t\telse\n\t\t\t{\n\t\t\tlc= -c1;\n\t\t\tdo\t{\n\t\t\t\tll=r[i];\n\t\t\t\tr[i++]=(ll-lc)&BN_MASK2;\n\t\t\t\tlc=(lc > ll);\n\t\t\t\t} while (lc);\n\t\t\t}\n\t\t}\n\tif (c2 != 0)\n\t\t{\n\t\ti=n;\n\t\tif (c2 > 0)\n\t\t\t{\n\t\t\tlc=c2;\n\t\t\tdo\t{\n\t\t\t\tll=(r[i]+lc)&BN_MASK2;\n\t\t\t\tr[i++]=ll;\n\t\t\t\tlc=(lc > ll);\n\t\t\t\t} while (lc);\n\t\t\t}\n\t\telse\n\t\t\t{\n\t\t\tlc= -c2;\n\t\t\tdo\t{\n\t\t\t\tll=r[i];\n\t\t\t\tr[i++]=(ll-lc)&BN_MASK2;\n\t\t\t\tlc=(lc > ll);\n\t\t\t\t} while (lc);\n\t\t\t}\n\t\t}\n\t}', 'void bn_mul_recursive(BN_ULONG *r, BN_ULONG *a, BN_ULONG *b, size_t n2,\n\t\t      int dna, int dnb, BN_ULONG *t)\n\t{\n\tint n=n2/2,c1,c2;\n\tint tna=n+dna, tnb=n+dnb;\n\tunsigned int neg,zero;\n\tBN_ULONG ln,lo,*p;\n# ifdef BN_COUNT\n\tfprintf(stderr," bn_mul_recursive %d%+d * %d%+d\\n",n2,dna,n2,dnb);\n# endif\n# ifdef BN_MUL_COMBA\n#  if 0\n\tif (n2 == 4)\n\t\t{\n\t\tbn_mul_comba4(r,a,b);\n\t\treturn;\n\t\t}\n#  endif\n\tif (n2 == 8 && dna == 0 && dnb == 0)\n\t\t{\n\t\tbn_mul_comba8(r,a,b);\n\t\treturn;\n\t\t}\n# endif\n\tif (n2 < BN_MUL_RECURSIVE_SIZE_NORMAL)\n\t\t{\n\t\tbn_mul_normal(r,a,n2+dna,b,n2+dnb);\n\t\tif ((dna + dnb) < 0)\n\t\t\tmemset(&r[2*n2 + dna + dnb], 0,\n\t\t\t\tsizeof(BN_ULONG) * -(dna + dnb));\n\t\treturn;\n\t\t}\n\tc1=bn_cmp_part_words(a,&(a[n]),tna,n-tna);\n\tc2=bn_cmp_part_words(&(b[n]),b,tnb,tnb-n);\n\tzero=neg=0;\n\tswitch (c1*3+c2)\n\t\t{\n\tcase -4:\n\t\tbn_sub_part_words(t,      &(a[n]),a,      tna,tna-n);\n\t\tbn_sub_part_words(&(t[n]),b,      &(b[n]),tnb,n-tnb);\n\t\tbreak;\n\tcase -3:\n\t\tzero=1;\n\t\tbreak;\n\tcase -2:\n\t\tbn_sub_part_words(t,      &(a[n]),a,      tna,tna-n);\n\t\tbn_sub_part_words(&(t[n]),&(b[n]),b,      tnb,tnb-n);\n\t\tneg=1;\n\t\tbreak;\n\tcase -1:\n\tcase 0:\n\tcase 1:\n\t\tzero=1;\n\t\tbreak;\n\tcase 2:\n\t\tbn_sub_part_words(t,      a,      &(a[n]),tna,n-tna);\n\t\tbn_sub_part_words(&(t[n]),b,      &(b[n]),tnb,n-tnb);\n\t\tneg=1;\n\t\tbreak;\n\tcase 3:\n\t\tzero=1;\n\t\tbreak;\n\tcase 4:\n\t\tbn_sub_part_words(t,      a,      &(a[n]),tna,n-tna);\n\t\tbn_sub_part_words(&(t[n]),&(b[n]),b,      tnb,tnb-n);\n\t\tbreak;\n\t\t}\n# ifdef BN_MUL_COMBA\n\tif (n == 4 && dna == 0 && dnb == 0)\n\t\t{\n\t\tif (!zero)\n\t\t\tbn_mul_comba4(&(t[n2]),t,&(t[n]));\n\t\telse\n\t\t\tmemset(&(t[n2]),0,8*sizeof(BN_ULONG));\n\t\tbn_mul_comba4(r,a,b);\n\t\tbn_mul_comba4(&(r[n2]),&(a[n]),&(b[n]));\n\t\t}\n\telse if (n == 8 && dna == 0 && dnb == 0)\n\t\t{\n\t\tif (!zero)\n\t\t\tbn_mul_comba8(&(t[n2]),t,&(t[n]));\n\t\telse\n\t\t\tmemset(&(t[n2]),0,16*sizeof(BN_ULONG));\n\t\tbn_mul_comba8(r,a,b);\n\t\tbn_mul_comba8(&(r[n2]),&(a[n]),&(b[n]));\n\t\t}\n\telse\n# endif\n\t\t{\n\t\tp= &(t[n2*2]);\n\t\tif (!zero)\n\t\t\tbn_mul_recursive(&(t[n2]),t,&(t[n]),n,0,0,p);\n\t\telse\n\t\t\tmemset(&(t[n2]),0,n2*sizeof(BN_ULONG));\n\t\tbn_mul_recursive(r,a,b,n,0,0,p);\n\t\tbn_mul_recursive(&(r[n2]),&(a[n]),&(b[n]),n,dna,dnb,p);\n\t\t}\n\tc1=bn_add_words(t,r,&(r[n2]),n2);\n\tif (neg)\n\t\t{\n\t\tc1-=bn_sub_words(&(t[n2]),t,&(t[n2]),n2);\n\t\t}\n\telse\n\t\t{\n\t\tc1+=bn_add_words(&(t[n2]),&(t[n2]),t,n2);\n\t\t}\n\tc1+=bn_add_words(&(r[n]),&(r[n]),&(t[n2]),n2);\n\tif (c1)\n\t\t{\n\t\tp= &(r[n+n2]);\n\t\tlo= *p;\n\t\tln=(lo+c1)&BN_MASK2;\n\t\t*p=ln;\n\t\tif (ln < (BN_ULONG)c1)\n\t\t\t{\n\t\t\tdo\t{\n\t\t\t\tp++;\n\t\t\t\tlo= *p;\n\t\t\t\tln=(lo+1)&BN_MASK2;\n\t\t\t\t*p=ln;\n\t\t\t\t} while (ln == 0);\n\t\t\t}\n\t\t}\n\t}', 'int bn_cmp_part_words(const BN_ULONG *a, const BN_ULONG *b,\n\tint cl, int dl)\n\t{\n\tint n,i;\n\tn = cl-1;\n\tif (dl < 0)\n\t\t{\n\t\tfor (i=dl; i<0; i++)\n\t\t\t{\n\t\t\tif (b[n-i] != 0)\n\t\t\t\treturn -1;\n\t\t\t}\n\t\t}\n\tif (dl > 0)\n\t\t{\n\t\tfor (i=dl; i>0; i--)\n\t\t\t{\n\t\t\tif (a[n+i] != 0)\n\t\t\t\treturn 1;\n\t\t\t}\n\t\t}\n\treturn bn_cmp_words(a,b,cl);\n\t}', 'BN_ULONG bn_sub_part_words(BN_ULONG *r,\n\t\t\t   const BN_ULONG *a, const BN_ULONG *b,\n\t\t\t   size_t cl, ssize_t dl)\n\t{\n\tBN_ULONG c, t;\n\tassert(cl >= 0);\n\tc = bn_sub_words(r, a, b, cl);\n\tif (dl == 0)\n\t\treturn c;\n\tr += cl;\n\ta += cl;\n\tb += cl;\n\tif (dl < 0)\n\t\t{\n#ifdef BN_COUNT\n\t\tfprintf(stderr, "  bn_sub_part_words %d + %d (dl < 0, c = %d)\\n", cl, dl, c);\n#endif\n\t\tfor (;;)\n\t\t\t{\n\t\t\tt = b[0];\n\t\t\tr[0] = (0-t-c)&BN_MASK2;\n\t\t\tif (t != 0) c=1;\n\t\t\tif (++dl >= 0) break;\n\t\t\tt = b[1];\n\t\t\tr[1] = (0-t-c)&BN_MASK2;\n\t\t\tif (t != 0) c=1;\n\t\t\tif (++dl >= 0) break;\n\t\t\tt = b[2];\n\t\t\tr[2] = (0-t-c)&BN_MASK2;\n\t\t\tif (t != 0) c=1;\n\t\t\tif (++dl >= 0) break;\n\t\t\tt = b[3];\n\t\t\tr[3] = (0-t-c)&BN_MASK2;\n\t\t\tif (t != 0) c=1;\n\t\t\tif (++dl >= 0) break;\n\t\t\tb += 4;\n\t\t\tr += 4;\n\t\t\t}\n\t\t}\n\telse\n\t\t{\n\t\tssize_t save_dl = dl;\n#ifdef BN_COUNT\n\t\tfprintf(stderr, "  bn_sub_part_words %d + %d (dl > 0, c = %d)\\n", cl, dl, c);\n#endif\n\t\twhile(c)\n\t\t\t{\n\t\t\tt = a[0];\n\t\t\tr[0] = (t-c)&BN_MASK2;\n\t\t\tif (t != 0) c=0;\n\t\t\tif (--dl <= 0) break;\n\t\t\tt = a[1];\n\t\t\tr[1] = (t-c)&BN_MASK2;\n\t\t\tif (t != 0) c=0;\n\t\t\tif (--dl <= 0) break;\n\t\t\tt = a[2];\n\t\t\tr[2] = (t-c)&BN_MASK2;\n\t\t\tif (t != 0) c=0;\n\t\t\tif (--dl <= 0) break;\n\t\t\tt = a[3];\n\t\t\tr[3] = (t-c)&BN_MASK2;\n\t\t\tif (t != 0) c=0;\n\t\t\tif (--dl <= 0) break;\n\t\t\tsave_dl = dl;\n\t\t\ta += 4;\n\t\t\tr += 4;\n\t\t\t}\n\t\tif (dl > 0)\n\t\t\t{\n#ifdef BN_COUNT\n\t\t\tfprintf(stderr, "  bn_sub_part_words %d + %d (dl > 0, c == 0)\\n", cl, dl);\n#endif\n\t\t\tif (save_dl > dl)\n\t\t\t\t{\n\t\t\t\tswitch (save_dl - dl)\n\t\t\t\t\t{\n\t\t\t\tcase 1:\n\t\t\t\t\tr[1] = a[1];\n\t\t\t\t\tif (--dl <= 0) break;\n\t\t\t\tcase 2:\n\t\t\t\t\tr[2] = a[2];\n\t\t\t\t\tif (--dl <= 0) break;\n\t\t\t\tcase 3:\n\t\t\t\t\tr[3] = a[3];\n\t\t\t\t\tif (--dl <= 0) break;\n\t\t\t\t\t}\n\t\t\t\ta += 4;\n\t\t\t\tr += 4;\n\t\t\t\t}\n\t\t\t}\n\t\tif (dl > 0)\n\t\t\t{\n#ifdef BN_COUNT\n\t\t\tfprintf(stderr, "  bn_sub_part_words %d + %d (dl > 0, copy)\\n", cl, dl);\n#endif\n\t\t\tfor(;;)\n\t\t\t\t{\n\t\t\t\tr[0] = a[0];\n\t\t\t\tif (--dl <= 0) break;\n\t\t\t\tr[1] = a[1];\n\t\t\t\tif (--dl <= 0) break;\n\t\t\t\tr[2] = a[2];\n\t\t\t\tif (--dl <= 0) break;\n\t\t\t\tr[3] = a[3];\n\t\t\t\tif (--dl <= 0) break;\n\t\t\t\ta += 4;\n\t\t\t\tr += 4;\n\t\t\t\t}\n\t\t\t}\n\t\t}\n\treturn c;\n\t}', 'BN_ULONG bn_sub_words(BN_ULONG *r, const BN_ULONG *a, const BN_ULONG *b, size_t n)\n        {\n\tBN_ULONG t1,t2;\n\tint c=0;\n\tassert(n >= 0);\n\tif (n <= 0) return((BN_ULONG)0);\n#ifndef OPENSSL_SMALL_FOOTPRINT\n\twhile (n&~3)\n\t\t{\n\t\tt1=a[0]; t2=b[0];\n\t\tr[0]=(t1-t2-c)&BN_MASK2;\n\t\tif (t1 != t2) c=(t1 < t2);\n\t\tt1=a[1]; t2=b[1];\n\t\tr[1]=(t1-t2-c)&BN_MASK2;\n\t\tif (t1 != t2) c=(t1 < t2);\n\t\tt1=a[2]; t2=b[2];\n\t\tr[2]=(t1-t2-c)&BN_MASK2;\n\t\tif (t1 != t2) c=(t1 < t2);\n\t\tt1=a[3]; t2=b[3];\n\t\tr[3]=(t1-t2-c)&BN_MASK2;\n\t\tif (t1 != t2) c=(t1 < t2);\n\t\ta+=4; b+=4; r+=4; n-=4;\n\t\t}\n#endif\n\twhile (n)\n\t\t{\n\t\tt1=a[0]; t2=b[0];\n\t\tr[0]=(t1-t2-c)&BN_MASK2;\n\t\tif (t1 != t2) c=(t1 < t2);\n\t\ta++; b++; r++; n--;\n\t\t}\n\treturn(c);\n\t}']