joyent/node

.text

.global    bn_mul_mont
.type    bn_mul_mont,%function

.align    2
bn_mul_mont:
    stmdb    sp!,{r0,r2}        @ sp points at argument block
    ldr    r0,[sp,#3*4]        @ load num
    cmp    r0,#2
    movlt    r0,#0
    addlt    sp,sp,#2*4
    blt    .Labrt

    stmdb    sp!,{r4-r12,lr}        @ save 10 registers

    mov    r0,r0,lsl#2        @ rescale r0 for byte count
    sub    sp,sp,r0        @ alloca(4*num)
    sub    sp,sp,#4        @ +extra dword
    sub    r0,r0,#4        @ "num=num-1"
    add    r4,r2,r0        @ &bp[num-1]

    add    r0,sp,r0        @ r0 to point at &tp[num-1]
    ldr    r8,[r0,#14*4]        @ &n0
    ldr    r2,[r2]        @ bp[0]
    ldr    r5,[r1],#4        @ ap[0],ap++
    ldr    r6,[r3],#4        @ np[0],np++
    ldr    r8,[r8]        @ *n0
    str    r4,[r0,#15*4]        @ save &bp[num]

    umull    r10,r11,r5,r2    @ ap[0]*bp[0]
    str    r8,[r0,#14*4]        @ save n0 value
    mul    r8,r10,r8        @ "tp[0]"*n0
    mov    r12,#0
    umlal    r10,r12,r6,r8    @ np[0]*n0+"t[0]"
    mov    r4,sp

.L1st:
    ldr    r5,[r1],#4        @ ap[j],ap++
    mov    r10,r11
    ldr    r6,[r3],#4        @ np[j],np++
    mov    r11,#0
    umlal    r10,r11,r5,r2    @ ap[j]*bp[0]
    mov    r14,#0
    umlal    r12,r14,r6,r8    @ np[j]*n0
    adds    r12,r12,r10
    str    r12,[r4],#4        @ tp[j-1]=,tp++
    adc    r12,r14,#0
    cmp    r4,r0
    bne    .L1st

    adds    r12,r12,r11
    ldr    r4,[r0,#13*4]        @ restore bp
    mov    r14,#0
    ldr    r8,[r0,#14*4]        @ restore n0
    adc    r14,r14,#0
    str    r12,[r0]        @ tp[num-1]=
    str    r14,[r0,#4]        @ tp[num]=


.Louter:
    sub    r7,r0,sp        @ "original" r0-1 value
    sub    r1,r1,r7        @ "rewind" ap to &ap[1]
    ldr    r2,[r4,#4]!        @ *(++bp)
    sub    r3,r3,r7        @ "rewind" np to &np[1]
    ldr    r5,[r1,#-4]        @ ap[0]
    ldr    r10,[sp]        @ tp[0]
    ldr    r6,[r3,#-4]        @ np[0]
    ldr    r7,[sp,#4]        @ tp[1]

    mov    r11,#0
    umlal    r10,r11,r5,r2    @ ap[0]*bp[i]+tp[0]
    str    r4,[r0,#13*4]        @ save bp
    mul    r8,r10,r8
    mov    r12,#0
    umlal    r10,r12,r6,r8    @ np[0]*n0+"tp[0]"
    mov    r4,sp

.Linner:
    ldr    r5,[r1],#4        @ ap[j],ap++
    adds    r10,r11,r7        @ +=tp[j]
    ldr    r6,[r3],#4        @ np[j],np++
    mov    r11,#0
    umlal    r10,r11,r5,r2    @ ap[j]*bp[i]
    mov    r14,#0
    umlal    r12,r14,r6,r8    @ np[j]*n0
    adc    r11,r11,#0
    ldr    r7,[r4,#8]        @ tp[j+1]
    adds    r12,r12,r10
    str    r12,[r4],#4        @ tp[j-1]=,tp++
    adc    r12,r14,#0
    cmp    r4,r0
    bne    .Linner

    adds    r12,r12,r11
    mov    r14,#0
    ldr    r4,[r0,#13*4]        @ restore bp
    adc    r14,r14,#0
    ldr    r8,[r0,#14*4]        @ restore n0
    adds    r12,r12,r7
    ldr    r7,[r0,#15*4]        @ restore &bp[num]
    adc    r14,r14,#0
    str    r12,[r0]        @ tp[num-1]=
    str    r14,[r0,#4]        @ tp[num]=

    cmp    r4,r7
    bne    .Louter


    ldr    r2,[r0,#12*4]        @ pull rp
    add    r0,r0,#4        @ r0 to point at &tp[num]
    sub    r5,r0,sp        @ "original" num value
    mov    r4,sp            @ "rewind" r4
    mov    r1,r4            @ "borrow" r1
    sub    r3,r3,r5        @ "rewind" r3 to &np[0]

    subs    r7,r7,r7        @ "clear" carry flag
.Lsub:    ldr    r7,[r4],#4
    ldr    r6,[r3],#4
    sbcs    r7,r7,r6        @ tp[j]-np[j]
    str    r7,[r2],#4        @ rp[j]=
    teq    r4,r0        @ preserve carry
    bne    .Lsub
    sbcs    r14,r14,#0        @ upmost carry
    mov    r4,sp            @ "rewind" r4
    sub    r2,r2,r5        @ "rewind" r2

    and    r1,r4,r14
    bic    r3,r2,r14
    orr    r1,r1,r3        @ ap=borrow?tp:rp

.Lcopy:    ldr    r7,[r1],#4        @ copy or in-place refresh
    str    sp,[r4],#4        @ zap tp
    str    r7,[r2],#4
    cmp    r4,r0
    bne    .Lcopy

    add    sp,r0,#4        @ skip over tp[num+1]
    ldmia    sp!,{r4-r12,lr}        @ restore registers
    add    sp,sp,#2*4        @ skip over {r0,r2}
    mov    r0,#1
.Labrt:    tst    lr,#1
    moveq    pc,lr            @ be binary compatible with V4, yet
    .word    0xe12fff1e            @ interoperable with Thumb ISA:-)
.size    bn_mul_mont,.-bn_mul_mont
.asciz    "Montgomery multiplication for ARMv4, CRYPTOGAMS by <appro@openssl.org>"
.align    2