some bigint stuff in ASM

[avr-crypto-lib.git] / bigint / bigint_adjust.S

diff --git a/bigint/bigint_adjust.S b/bigint/bigint_adjust.S
new file mode 100644 (file)
index 0000000..56ff2a1
--- /dev/null
+++ b/bigint/bigint_adjust.S
@@ -0,0 +1,110 @@
+/* bigint_adjust.S */
+/*
+    This file is part of the ARM-Crypto-Lib.
+    Copyright (C) 2006-2010 Daniel Otte (daniel.otte@rub.de)
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+/*
+void bigint_adjust(bigint_t* a){
+       while(a->length_B!=0 && a->wordv[a->length_B-1]==0){
+               a->length_B--;
+       }
+       if(a->length_B==0){
+               a->info=0;
+               return;
+       }
+       uint8_t t;
+       uint8_t i = 0x07;
+       t = a->wordv[a->length_B-1];
+       while((t&0x80)==0 && i){
+               t<<=1;
+               i--;
+       }
+       SET_FBS(a, i);
+}
+*/
+.global bigint_adjust
+bigint_adjust:
+       movw r30, r24
+       ldd r24, Z+0
+       ldd r25, Z+1
+       ldd r26, Z+3
+       ldd r27, Z+4
+       add r26, r24
+       adc r27, r25
+20:
+       sbiw r24, 1
+       brmi 30f
+       ld r23, -X
+       tst r23
+       brne 40f
+       rjmp 20b
+30:
+       std Z+0, r1
+       std Z+0, r1
+       std Z+2, r1
+       ret
+40:
+       adiw r24, 1
+       std Z+0, r24
+       std Z+1, r25
+       clr r24
+50:
+       sbrc r23, 0
+       mov r25, r24
+       lsr r23
+       inc r24
+       brpl 50b
+       ldd r23, Z+2
+       andi r23, 0xF8
+       or r23, r25
+       std Z+2, r23
+bigint_adjust_ret:
+       ret
+
+/*
+void bigint_copy(bigint_t* dest, const bigint_t* src){
+       memcpy(dest->wordv, src->wordv, src->length_B);
+       dest->length_B = src->length_B;
+       dest->info = src->info;
+}
+*/
+.global bigint_copy
+bigint_copy:
+       movw r26, r24
+       movw r30, r22
+       /* copy length */
+       ld r24, Z+
+       st X+, r24
+       ld r25, Z+
+       st X+, r25
+       /* copy info */
+       ld r22, Z+
+       st X+, r22
+       /* load wordv pointers */
+       ld r22, Z+
+       ld r23, Z
+       movw r30, r22
+       ld r22, X+
+       ld r23, X
+       movw r26, r22
+10:
+       sbiw r24, 1
+       brmi bigint_adjust_ret
+       ld r22, Z+
+       st X+, r22
+       rjmp 10b
+