even more serpent in asm

[avr-crypto-lib.git] / serpent-asm.S

diff --git a/serpent-asm.S b/serpent-asm.S
index a16f6af26bf2c97bc028d39b17d104b165ab7fe8..1005fd368b56ac1ceed0735ba90d3e172668cd52 100644 (file)
--- a/serpent-asm.S
+++ b/serpent-asm.S
@@ -538,6 +538,9 @@ static uint32_t serpent_gen_w(uint32_t * b, uint8_t i){
  * param i is passed in r22
  * return value is returned in r22.r23.r24.r25
  */
+ /* trashes:
+  *  r20-r25, r30-r31
+  */
 .global serpent_gen_w
 serpent_gen_w:
        movw r30, r24
@@ -589,3 +592,120 @@ serpent_gen_w:
        brne 1b
        ret
 
+/*
+ * void serpent_init(const void* key, uint16_t keysize_b, serpent_ctx_t* ctx)
+ */
+/*
+ * param key     is passed in r24:r25
+ * param keysize is passed in r22:r23
+ * param ctx     is passed in r20:r21
+ */
+.global serpent_init
+serpent_init:
+    stack_alloc 32
+    adiw r30, 1
+       push_ r30, r31
+    movw r26, r22
+    adiw r26, 7
+    tst r27
+    breq 1f
+       ldi r26, 32
+       rjmp 2f
+1:
+       lsr r26
+       lsr r26
+       lsr r26
+2:     
+       mov r22, r26
+       bst r22, 5 /* store in T if we have to do the "append 1 thing"*/
+       ldi r27, 32
+3:     /* set buffer to zero */
+       st Z+, r1
+       dec r27
+       brne 3b
+       
+       movw r26, r24 /* X points to the key */
+       sbiw r30, 32
+       tst r22
+       breq 5f /* if keylength_b==0 */
+4:     /* copy keybytes to buffer */
+       ld r19, X+
+       st Z+, r19
+       dec r22
+       brne 4b
+5:
+       brts 7f /* if keylength_b == 256 */
+       ldi r18, 0x01
+       andi r22, 0x07
+       brne 6f
+       st Z, r18
+       rjmp 7f
+6:     /* shift the one to the right position */
+       lsl r18
+       dec r22
+       brne 6b
+       or r18, r19
+       st -Z, r18
+7: /* post "appending 1 thing" buffer is ready for subkey generation */
+       movw r26, r20  /* X points to the context */
+       
+       pop_ r19, r18 /* r18:r19 points to the buffer */
+       push r16
+       clr r16
+8:
+       movw r24, r18
+       mov  r22, r16
+       rcall serpent_gen_w
+       movw r30, r18
+       ldi r20, 7*4
+1: /* the memmove */
+       ldd r0, Z+4
+       st Z+, r0
+       dec r20
+       brne 1b
+  /* store new word in buffer and context */   
+       st Z+, r22
+       st Z+, r23
+       st Z+, r24
+       st Z+, r25
+       st X+, r22
+       st X+, r23
+       st X+, r24
+       st X+, r25
+       
+       inc r16
+       cpi r16, 132
+       brne 8b 
+       
+       push_ r28, r29
+       movw r28, r26
+       subi r28, lo8(132*4)
+       sbci r29, hi8(132*4)
+       ldi r16, 33
+2:
+       movw r24, r28
+       adiw r28, 16
+       ldi r22, 2
+       add r22, r16
+       rcall sbox128
+       dec r16
+       brne 2b
+       pop_ r29, r28, r16
+       stack_free 32
+       ret
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+