x86_64-mont.pl readability improvement.

diff --git a/crypto/bn/asm/x86_64-mont.pl b/crypto/bn/asm/x86_64-mont.pl
index 7f3a43672a5aee21cb29eaf606e582f2571b1531..f3d112f8ff89ca45ba9ee13d0e59c3094deaabaf 100755 (executable)
--- a/crypto/bn/asm/x86_64-mont.pl
+++ b/crypto/bn/asm/x86_64-mont.pl
@@ -97,8 +97,8 @@ bn_mul_mont:
        xor     %rdx,%rdx
        add     $hi0,$hi1
        adc     \$0,%rdx
-       mov     $hi1,-8(%rsp,$j,8)
-       mov     %rdx,(%rsp,$j,8)
+       mov     $hi1,-8(%rsp,$num,8)
+       mov     %rdx,(%rsp,$num,8)      # store upmost overflow bit
 
        lea     1($i),$i                # i++
 .align 4
@@ -146,26 +146,25 @@ bn_mul_mont:
        cmp     $num,$j
        jl      .Linner
 
-       xor     %rdx,%rdx               # $j equals to num here...
+       xor     %rdx,%rdx
        add     $hi0,$hi1
        adc     \$0,%rdx
-       add     (%rsp,$j,8),$hi1        # pull upmost overflow bit
+       add     (%rsp,$num,8),$hi1      # pull upmost overflow bit
        adc     \$0,%rdx
-       mov     $hi1,-8(%rsp,$j,8)
-       mov     %rdx,(%rsp,$j,8)        # store upmost overflow bit
+       mov     $hi1,-8(%rsp,$num,8)
+       mov     %rdx,(%rsp,$num,8)      # store upmost overflow bit
 
        lea     1($i),$i                # i++
        cmp     $num,$i
        jl      .Louter
 
-       sub     $i,$i                   # clear CF at once
-       cmp     \$0,%rdx                # %rdx still holds upmost overflow bit
-       jnz     .Lsub                   # ... and $j still equals to num
-       mov     -8(%rsp,$num,8),%rax
-       cmp     -8($np,$num,8),%rax     # tp[num-1]-np[num-1]
-       jae     .Lsub
-
+       xor     $i,$i                   # i=0
        lea     -1($num),$j             # j=num-1
+       cmp     \$0,%rdx                # %rdx still holds upmost overflow bit
+       jnz     .Lsub                   # CF is cleared by compare with 0
+       mov     (%rsp,$j,8),%rax
+       cmp     ($np,$j,8),%rax         # tp[num-1]-np[num-1]
+       jae     .Lsub                   # if taken CF was cleared by above cmp
 .align 4
 .Lcopy:
        mov     (%rsp,$j,8),%rax
@@ -190,8 +189,8 @@ bn_mul_mont:
        sbb     ($np,$i,8),%rax
        mov     %rax,($rp,$i,8)         # rp[i]=tp[i]-np[j]
        lea     1($i),$i                # i++
-       dec     $j                      # doesn't affect cf!
-       jg      .Lsub
+       dec     $j                      # doesn't affect CF!
+       jge     .Lsub
        lea     -1($num),$j             # j=num-1
        sbb     \$0,%rdx
        jc      .Lcopy                  # tp was less than np