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# *****************************************************************
#
# The Compcert verified compiler
#
# Xavier Leroy, INRIA Paris-Rocquencourt
#
# Copyright (c) 2013 Institut National de Recherche en Informatique et
# en Automatique.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
# * Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# * 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.
# * Neither the name of the <organization> nor the
# names of its contributors may be used to endorse or promote products
# derived from this software without specific prior written permission.
#
# 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 <COPYRIGHT
# HOLDER> 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.
#
# *********************************************************************
# Helper functions for 64-bit integer arithmetic. PowerPC version.
.text
# Unsigned division and modulus
# This function computes both the quotient and the remainder of two
# unsigned 64-bit integers.
# Input: numerator N in (r3,r4), divisor D in (r5,r6)
# Output: quotient Q in (r7,r8), remainder R in (r3,r4)
# Locals: mask M in (r9,r10)
.globl __i64_udivmod
.balign 16
__i64_udivmod:
# Set up quotient and mask
li r8, 0 # Q = 0
li r7, 0
li r10, 1 # M = 1
li r9, 0
# Check for zero divisor
or. r0, r6, r5
beqlr # return with unspecified quotient & remainder
# Scale divisor and mask
1: cmpwi r5, 0 # while top bit of D is zero...
blt 2f
subfc r0, r6, r4 # compute borrow out of N - D
subfe r0, r5, r3
subfe. r0, r0, r0 # EQ iff no borrow iff N >= D
bne 2f # ... and while N >= D ...
addc r6, r6, r6 # scale divisor: D = D << 1
adde r5, r5, r5
addc r10, r10, r10 # scale mask: M = M << 1
adde r9, r9, r9
b 1b # end while
# Long division
2: subfc r4, r6, r4 # Q = Q | M, N = N - D, and compute borrow
or r8, r8, r10
subfe r3, r5, r3
or r7, r7, r9
subfe. r0, r0, r0 # test borrow
beq 3f # no borrow: N >= D, continue
addc r4, r4, r6 # borrow: undo what we just did to N and Q
andc r8, r8, r10
adde r3, r3, r5
andc r7, r7, r9
3: slwi r0, r9, 31 # unscale mask: M = M >> 1
srwi r10, r10, 1
or r10, r10, r0
srwi r9, r9, 1
slwi r0, r5, 31 # unscale divisor: D = D >> 1
srwi r6, r6, 1
or r6, r6, r0
srwi r5, r5, 1
or. r0, r10, r9 # iterate while M != 0
bne 2b
blr
.type __i64_udivmod, @function
.size __i64_udivmod, .-__i64_udivmod
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