243 lines
4.8 KiB
ArmAsm
243 lines
4.8 KiB
ArmAsm
/* bigint_asm.S */
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/*
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This file is part of the ARM-Crypto-Lib.
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Copyright (C) 2006-2010 Daniel Otte (daniel.otte@rub.de)
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "avr-asm-macros.S"
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#include "bigint_adjust.S"
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#include "bigint_add_u.S"
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/******************************************************************************/
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/*
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void bigint_add_scale_u(bigint_t *dest, const bigint_t *a, uint16_t scale){
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uint16_t i,j=0;
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uint16_t t=0;
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if(scale>dest->length_B)
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memset(dest->wordv+dest->length_B, 0, scale-dest->length_B);
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for(i=scale; i<a->length_B+scale; ++i,++j){
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t = a->wordv[j] + t;
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if(dest->length_B>i){
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t += dest->wordv[i];
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}
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dest->wordv[i] = (uint8_t)t;
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t>>=8;
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}
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while(t){
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if(dest->length_B>i){
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t = dest->wordv[i] + t;
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}
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dest->wordv[i] = (uint8_t)t;
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t>>=8;
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++i;
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}
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if(dest->length_B < i){
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dest->length_B = i;
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}
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bigint_adjust(dest);
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}
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*/
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DST_SIZE_0 = 22
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DST_SIZE_1 = 23
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SRC_SIZE_0 = 20
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SRC_SIZE_1 = 23
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SCALE_0 = 18
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SCALE_1 = 19
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DST_CTX_0 = 6
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DST_CTX_1 = 7
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SRC_CTX_0 = 8
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SRC_CTX_1 = 9
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TMP_0 = 10
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TMP_1 = 11
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.global bigint_add_scale_u
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/******************************************************************************/
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/******************************************************************************/
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/******************************************************************************/
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DST_LEN_0 = 22
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DST_LEN_1 = 23
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SRC_LEN_0 = 20
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SRC_LEN_1 = 21
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SCALE_0 = 18
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SCALE_1 = 19
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DST_CTX_0 = 8
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DST_CTX_1 = 9
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TMP_0 = 10
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TMP_1 = 11
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bigint_add_scale_u:
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movw r30, r24 /* dest ptr */
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movw r26, r22 /* src ptr */
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movw r24, r20 /* scale */
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/* check if scale is zero */
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movw SCALE_0, r24
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adiw r24, 0
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brne 10f
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movw r24, r30
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movw r20, r30
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rjmp bigint_add_u
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10: /* check if src is zero */
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ld r24, X+
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ld r25, X+
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adiw r24, 0
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brne 10f
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ret
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10:
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movw SRC_LEN_0, r24
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push_range 8, 11
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movw DST_CTX_0, r30
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/* pad dest with zeros to length of SRC_LENGTH + scale */
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adiw r26, 1
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ld TMP_0, X+
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ld TMP_1, X+
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movw r26, TMP_0 /* move SRC_WORDV to X */
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ldd DST_LEN_0, Z+0
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ldd DST_LEN_1, Z+1
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ldd TMP_0, Z+3
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ldd TMP_1, Z+4
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movw r30, TMP_0 /* move DEST_WORDV to Z */
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movw TMP_0, SCALE_0
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sub TMP_0, DST_LEN_0
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sbc TMP_1, DST_LEN_1
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movw r24, TMP_0
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brmi 40f /* no padding needed since DST_LEN > scale */
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add r30, DST_LEN_0 /* add DST_LEN to Z (DEST_WORDV)*/
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adc r31, DST_LEN_1
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/* pad and copy src in front of dest */
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10: /* padding loop */
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sbiw r24, 1
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brmi 11f
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st Z+, r1
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rjmp 10b
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11:
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/* start of copy */
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movw r24, SRC_LEN_0
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12: /* copy loop */
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sbiw r24, 1
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brmi 13f
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ld TMP_0, X+
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st Z+, TMP_0
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rjmp 12b
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13:
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movw TMP_0, SCALE_0
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add TMP_0, SRC_LEN_0
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adc TMP_1, SRC_LEN_1
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movw r30, DST_CTX_0
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std Z+0, TMP_0
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std Z+1, TMP_1
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movw r24, r30
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99:
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pop_range 8, 11
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rjmp bigint_adjust
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40:
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/* Z points at DST_WORDV */
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/* X points at SRC_WORDV */
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/* r24:r25 and TMP contain scale - DST_LEN (negativ) */
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/* set T bit if DST_LEN > SCR_LEN + scale */
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clt
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add r30, SCALE_0
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adc r31, SCALE_1
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add TMP_0, SRC_LEN_0
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adc TMP_1, SRC_LEN_1
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brpl 41f
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set
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/* DST_LEN > SRC_LEN + scale && DST_LEN > scale */
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/*
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+-------+-------+ SRC + scale
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+------+------------+ DST
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*/
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movw r24, SRC_LEN_0
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rjmp 44f
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41:
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/* DST_LEN <= SRC_LEN + scale && DST_LEN > scale */
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/*
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+-------+-------+ SRC + scale
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+------------+ DST
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*/
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com r24 /* negate r24:r25 ==> DST_LEN - scale */
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com r25
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adiw r24, 1
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breq 50f
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44:
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inc r25
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clc
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45:
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46: ld TMP_0, X+
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ld TMP_1, Z
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adc TMP_0, TMP_1
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st Z+, TMP_0
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dec r24
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brne 46b
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dec r25
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brne 46b
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50: ;st Z, r1
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brtc 60f
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51: brcc 53f
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52: ld TMP_0, Z
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adc TMP_0, r1
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st Z+, TMP_0
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brcs 52b
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53:
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/* epilogue */
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movw r24, r30
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movw r30, DST_CTX_0
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ldd TMP_0, Z+3
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ldd TMP_1, Z+4
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sub r24, TMP_0
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sbc r25, TMP_1
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cp r24, DST_LEN_0
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cpc r25, DST_LEN_1
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brmi 54f
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std Z+0, r24
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std Z+1, r25
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54: movw r24, r30
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rjmp 99b
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60: st Z, r1
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rol r1 /* backup carry */
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movw r24, SRC_LEN_0
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add r24, SCALE_0
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adc r25, SCALE_1
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sub r24, DST_LEN_0
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sbc r25, DST_LEN_1
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adiw r24, 0
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breq 63f
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inc r25
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ror r1 /* restore carry */
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61:
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62: ld TMP_0, X+
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adc TMP_0, r1
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st Z+, TMP_0
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dec r24
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brne 62b
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dec r25
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brne 62b
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63:
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brcc 53b
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ldi r24, 1
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st Z+, r24
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rjmp 53b
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