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/*
* Copyright (c) 2014, STMicroelectronics International N.V.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
.syntax unified
.thumb
.section .text
.align 2
.global __mpa_full_adder
.global __mpa_full_sub
.global __mpa_full_adder_ackum
.global __mpa_div_dword
.global __mpa_mul_add_word
.global __mpa_mul_add_word_cum
.global __mpa_montgomery_mul_add
.global __mpa_montgomery_sub_ack
@ --------------------------------------------------------------------
@ Function: __mpa_full_adder
@
@ A word_t sized full adder. Incoming carry is in *carry.
@ The sum will be put in *sum and the
@ outgoing carry will be returned in *carry
@
@ void __mpa_full_adder( mpa_word_t a,
@ mpa_word_t b,
@ mpa_word_t* sum,
@ mpa_word_t* carry)
@
.thumb_func
.type __mpa_full_adder, %function
__mpa_full_adder:
push {r9}
ldr r9, [r3] @ r9 holds incoming carry
adds r1, r1, r0 @ r1 holds b + a
mov r12, #0 @
adc r0, r12, #0 @ r0 holds carry of a + b
adds r1, r1, r9 @ r1 holds a + b + incoming carry
str r1, [r2] @ *sum <- r1
adc r0, r0, #0 @ r0 holds acc carry
str r0, [r3] @ *carry <- r0
pop {r9}
bx lr
@ --------------------------------------------------------------------
@ Function: __mpa_full_sub
@
@ A word_t sized full subtraction function. Incoming carry is in *carry
@ The difference will be put in *diff and the outgoing carry will be returned
@ in *carry
@
@ void __mpa_full_sub(mpa_word_t a,
@ mpa_word_t b,
@ mpa_word_t* diff,
@ mpa_word_t* carry);
@
.thumb_func
.type __mpa_full_sub, %function
__mpa_full_sub:
push {r9}
ldr r9, [r3] @ r9 holds incomming carry
subs r1, r0, r1 @ r1 holds a - b
mov r12, #0
sbc r0, r12, #0 @ r0 holds carry
subs r1, r1, r9 @ r1 holds a - b - carry
str r1, [r2] @ *diff <- r1
sbc r0, r0, #0 @ r0 <- r0 - carry
rsbs r0, r0, #0 @ r0 <- 0 - r0 outgoing carry
str r0, [r3] @ *carry <- r0
pop {r9}
bx lr
@ --------------------------------------------------------------------
@ Function: __mpa_full_adder_ackum
@
@ A word_t sized full adder with ackumulate. *d = *d + e + *carry
@ Outgoing carry is in *carry
@
@ void __mpa_full_adder_ackum( mpa_word_t* d,
@ mpa_word_t e,
@ mpa_word_t* carry)
@
.thumb_func
.type __mpa_full_adder_ackum, %function
__mpa_full_adder_ackum:
push {r9}
ldr r12, [r0] @ r12 <- *d
mov r9, #0 @
ldr r3, [r2] @ r3 holds incoming carry
adds r1, r1, r12 @ r1 <- e + *d
adc r9, r9, #0 @ r9 <- carry
adds r1, r1, r3 @ r1 <- r1 + *carry
str r1, [r0] @ *d <- sum
adc r0, r9, #0 @ r0 <- outgoing carry
str r0, [r2] @ *carry <- carry
pop {r9}
bx lr
@ --------------------------------------------------------------------
@ Function: __mpa_div_dword
@
@ Wrapper for the soft div. Calculates quotient and remainder of
@ ((x1 << WORD_SIZE) + x0 ) / y
@
@ mpa_word_t __mpa_div_dword(mpa_word_t x0,
@ mpa_word_t x1,
@ mpa_word_t y,
@ mpa_word_t* rem)
@
@ returns the quotient in r0 and the remainder in *rem
@
@ At entrace
@ r0 low32 of num
@ r1 high32 of num
@ r2 y (becomes high32 of den)
@ r3 addr of rem
.thumb_func
.type __mpa_div_dword, %function
__mpa_div_dword:
push {r4, r5, r6, r7, r8, r9, lr}@
mov r12, #0 @ r12 holds low32 of den
@ r2 holds high32 of den
mov lr, #1 @ lr holds high32 of qbit
movs r4, #0 @ r4 holds low32 of qbit
cmp r2, #-1 @ if den >= 0
bgt normalize @ branch to normalize
mov r9, #0 @ r9 holds low of quot
mov r8, #0 @ r8 holds high of quot
soft_div_main:
cmp r12, r0 @ cmp low(den) low(num)
mov r6, #0 @
it hi @
movhi r6, #1 @ r6 is 1 if low(den) > low(num)
cmp r2, r1 @ cmp high(den) high(num)
mov r5, #0 @
it hi @
movhi r5, #1 @ r5 if 1 if high(den) > high(num)
it eq @
moveq r5, r6 @ if high is equal let low decide
cbnz r5, shift_right @ if r5 == 1 branch
adds r9, r9, r4 @ quot += qbit
adc r8, r8, lr @
subs r0, r0, r12 @ num -= den
sbcs r1, r2 @
shift_right:
@
@ These right shifts should be done as
@
@ lsrs r2, r2, #1 @ right shift den >>= 1
@ rrx r12, r12
@ lsrs lr, lr, #1 @ right shift qbit >>= 1
@ rrx r4, r4
@
@ but due to a compiler error in the STE toolchain (2012-05-03)
@ we must implement this as:
and r7, r2, #1
mov r2, r2, lsr #1
mov r7, r7, lsl #31
mov r12, r12, lsr #1
orr r12, r12, r7
and r7, lr, #1
mov lr, lr, lsr #1
mov r7, r7, lsl #31
mov r4, r4, lsr #1
orr r4, r4, r7
@
@ end of compiler bug fix
@
orrs r5, r4, lr @ while qbit != 0
bne soft_div_main @ do mainloop
store_and_exit:
cmp r3, #0 @ if (r != NULL)
it ne @
strne r0, [r3] @ store remainder into *r
mov r0, r9 @
pop {r4, r5, r6, r7, r8, r9, pc}@ clean up and exit
normalize:
adds r4, r4, r4 @ qbit <<= 1
adc lr, lr, lr @
adds r12, r12, r12 @ den <<= 1
adcs r2, r2 @
cmp r2, #-1 @ while den >= 0
bgt normalize @ do normalize
mov r9, #0 @
orrs r6, r4, lr @ if qbit == 0
beq store_and_exit @ done, branch to store r and exit
mov r8, r9 @ set quot = 0 (r9 = 0 r8 = 0)
b soft_div_main @ and branch to main loop
@ --------------------------------------------------------------------
@ Function: __mpa_mul_add_word
@
@ Multiplies a and b and adds the incoming carry tp produce the product.
@ Outgoing carry is stored in *carry
@
@ void __mpa_mul_add_word(mpa_word_t a,
@ mpa_word_t b,
@ mpa_word_t* p,
@ mpa_word_t* carry)
@
@
.thumb_func
.type __mpa_mul_add_word, %function
__mpa_mul_add_word:
push {r9}
umull r1, r9, r1, r0 @ r1, r9 <- a * b
ldr r0, [r3] @ r0 <- incoming carry
adds r1, r1, r0 @ add incoming carry to product
str r1, [r2] @ store low32 of product
adc r0, r9, #0 @ add carry to high32
str r0, [r3] @ store outgoing carry
pop {r9}
bx lr
@ --------------------------------------------------------------------
@ Function: __mpa_mul_add_word_cum
@
@ Multiplies a and b and adds the incoming carry and the cumulative
@ product.
@ Outgoing carry is stored in *carry
@
@ void __mpa_mul_add_word_cum(mpa_word_t a,
@ mpa_word_t b,
@ mpa_word_t* p,
@ mpa_word_t* carry)
@
@
.thumb_func
.type __mpa_mul_add_word_cum, %function
__mpa_mul_add_word_cum:
push {r9}
umull r12, r9, r1, r0 @ r9, r12 <- a * b
ldr r0, [r2] @ r0 holds incoming product
ldr r1, [r3] @ r1 holds incoming carry
adds r0, r0, r12 @ r0 holds incoming product + new low32
adc r9, r9, #0 @ add carry to high32
adds r0, r0, r1 @ add incoming carry
str r0, [r2] @ store outgoing product
adc r0, r9, #0 @ store outgoing carry in r0
str r0, [r3] @ and write to [r3]
pop {r9}
bx lr
@ --------------------------------------------------------------------
@ Function: __mpa_montgomery_mul_add
@
@ Calculates dest = dest + src * w
@ Dest must be big enough to hold the result
@
@ void __mpa_montgomery_mul_add(mpanum dest,
@ mpanum src,
@ mpa_word_t w)
@
.thumb_func
.type __mpa_montgomery_mul_add, %function
__mpa_montgomery_mul_add:
push {r4, r5, r6, r7, lr}
add r7, sp, #12
push {r8, r9, r10, r11}
cbz r2, mm_mul_add_exit @ if w == 0 return
ldr r3, [r1, #4] @ r3 holds src->size
add r9, r0, #8 @ r9 holds &dest->d (dest_begin)
cmp r3, #1 @
mov r3, r9 @ r3 holds &dest->d (ddig)
blt mm_mul_add_check_size @ if src->size == NULL jump
add r12, r1, #8 @ r12 holds &src->d
mov lr, #0 @
movs r3, #0 @
movs r4, #0 @ r4 holds carry
movs r5, #0 @ r5 holds inx
mm_main_loop:
ldr r6, [r12, r5, lsl #2] @ r6 holds src->d[idx]
adds r3, #4
ldr r11, [r9, r5, lsl #2] @ r11 holds dest->d[idx]
umull r10, r8, r6, r2 @ r8, r10 holds src->d[idx] * w
mla r8, r6, lr, r8 @ r8 <- r6*0 + r8 ??
adds r6, r11, r4 @ r6 <- dest->d[idx] + carry
adc r4, lr, #0 @ r4 holds C
adds r6, r6, r10 @ r6 holds low32 of result
str r6, [r9, r5, lsl #2] @ store into dest->d[idx]
add r5, r5, #1 @ idx++
ldr r6, [r1, #4] @ r6 holds src->size
adc r4, r4, r8 @ r4 holds high32 of result
cmp r5, r6 @ while (idx < src->size)
blt mm_main_loop @ do jump
adds r1, r0, r3 @
cmp r4, #0 @ check carry
add r3, r1, #8 @ r3 holds &dest->d[idx]
beq mm_mul_add_check_size @ jump if no carry
movs r1, #0
mm_carry_loop:
ldr r2, [r3] @ r2 holds dest->d[idx]
adds r2, r2, r4 @ r2 <- r2 + carry
str r2, [r3], #4 @ store at dest->d[idx++]
adcs r4, r1, #0 @ r4 holds new C
bne mm_carry_loop @ if r4 != 0 jump
mm_mul_add_check_size:
sub r1, r3, r9 @ r1 holds ddig - dest_begin
ldr r2, [r0, #4] @ r2 holds dest->size
asrs r1, r1, #2 @ mult by 2 to go from byte addr to word
cmp r1, r2 @
it gt @
strgt r1, [r0, #4] @ store new size if idx > dest->size
mm_mul_add_exit:
pop {r8, r9, r10, r11}
pop {r4, r5, r6, r7, pc}
@ --------------------------------------------------------------------
@ Function: __mpa_montgomery_sub_ack
@ Calculates dest = dest - src
@ Assumption: dest >= src and both non-negative
@ and dest > src.
@
@
@ void __mpa_montgomery_sub_ack(mpanum dest,
@ mpanum src)
@
.thumb_func
.type __mpa_montgomery_sub_ack, %function
__mpa_montgomery_sub_ack:
push {r4, r5, r7, r9, lr}
ldr r2, [r1, #4]
add r9, r0, #8
mov lr, #0
add r7, sp, #8
cmp r2, #0
bgt LBB1_10
movs r2, #0
b LBB1_6
LBB1_2:
cbz r4, LBB1_6
movs r1, #0
LBB1_4:
add r5, r0, r2, lsl #2
adds r3, #4
adds r2, #1
ldr r4, [r5, #8]
subs r4, r4, r12
str r4, [r5, #8]
sbcs r5, r1, #0
rsb r12, r5, #0
bne LBB1_4
add r9, r0, r3
LBB1_6:
ldr r3, [r0, #4]
cmp r2, r3
blt LBB1_12
sub r1, r9, #4
subs r2, r3, #1
LBB1_8:
adds r3, r2, #1
cmp r3, #1
blt LBB1_12
ldr r3, [r1]
cmp r3, #0
it ne
popne {r4, r5, r7, r9, pc}
str r2, [r0, #4]
subs r2, #1
subs r1, #4
b LBB1_8
LBB1_10:
movs r3, #8
movs r2, #0
mov r12, #0
LBB1_11:
add r5, r1, r2, lsl #2
ldr r4, [r9]
adds r3, #4
adds r2, #1
ldr r5, [r5, #8]
subs r5, r4, r5
sbc r4, lr, #0
subs r5, r5, r12
str r5, [r9], #4
sbc r4, r4, #0
ldr r5, [r1, #4]
rsb r12, r4, #0
cmp r2, r5
blt LBB1_11
b LBB1_2
LBB1_12:
pop {r4, r5, r7, r9, pc}
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