* x86_64/serpent-encrypt.asm: Slight simplification of loop logic.

Rev: nettle/x86_64/serpent-encrypt.asm:1.2

diff --git a/x86_64/serpent-encrypt.asm b/x86_64/serpent-encrypt.asm
index 9172b7fbe91975be502edc5700c5f46261325b57..9b7a25b5785e97ea0eaf51aec3903dd09f26f8b9 100644 (file)
--- a/x86_64/serpent-encrypt.asm
+++ b/x86_64/serpent-encrypt.asm
@@ -296,9 +296,6 @@ define(<LT>, <
        .text
        ALIGN(4)
 PROLOGUE(nettle_serpent_encrypt)
-       test    N, N
-       jz      .Lend
-
         C save all registers that need to be saved
        push    %rbx
        push    %rbp
@@ -309,7 +306,11 @@ PROLOGUE(nettle_serpent_encrypt)
        lea     (SRC, N), SRC
        lea     (DST, N), DST
        neg     N
-       
+       jz      .Lend
+
+       C Point at the final subkey.
+       lea     512(CTX), CTX
+
 C The single-block loop here is slightly slower than the double-block
 C loop in serpent-encrypt.c.
 
@@ -319,8 +320,13 @@ C loop in serpent-encrypt.c.
        movl    8(SRC, N), x2
        movl    12(SRC, N), x3
 
-       xor     CNT, CNT
+       mov     $-512, CNT
+       jmp     .Lround_start
+       
+       ALIGN(4)
 .Lround_loop:
+       LT(x0,x1,x2,x3)
+.Lround_start:
        xor       (CTX, CNT), x0
        xor      4(CTX, CNT), x1
        xor      8(CTX, CNT), x2
@@ -376,13 +382,9 @@ C loop in serpent-encrypt.c.
        xor     124(CTX, CNT), y3
        SBOX7(y0,y1,y2,y3, x0,x1,x2,x3)
        add     $128, CNT
-       C FIXME: Offset CTX and CNT, so we can jump out when CNT == 0
-       cmp     $512, CNT
-       je      .Lfinal_round
-       LT(x0,x1,x2,x3)
-       jmp     .Lround_loop
+       jnz     .Lround_loop
 
-.Lfinal_round:
+       C Apply final subkey.
        xor       (CTX, CNT), x0
        xor      4(CTX, CNT), x1
        xor      8(CTX, CNT), x2
@@ -394,12 +396,11 @@ C loop in serpent-encrypt.c.
        movl    x3, 12(DST, N)
        add     $16, N
        jnc     .Lblock_loop
-       
 
+.Lend:
        pop     %r14
        pop     %r13
        pop     %r12
        pop     %rbp
        pop     %rbx
-.Lend:
        ret