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# *****************************************************************
#
# The Compcert verified compiler
#
# Xavier Leroy, INRIA Paris
#
# Copyright (c) 2016 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
### Signed multiply-high
# Hacker's Delight section 8.3:
# - compute high 64 bits of the unsigned product X * Y (see i64_umulh.S)
# - subtract X if Y < 0
# - subtract Y if X < 0
.balign 16
.globl __compcert_i64_smulh
__compcert_i64_smulh:
# r7:r8:r9 accumulate bits 127:32 of the full unsigned product
mulhwu r9, r4, r6 # r9 = high half of XL.YL
mullw r0, r4, r5 # r0 = low half of XL.YH
addc r9, r9, r0
mulhwu r0, r4, r5 # r0 = high half of XL.YH
addze r8, r0
mullw r0, r3, r6 # r0 = low half of XH.YL
addc r9, r9, r0
mulhwu r0, r3, r6 # r0 = high half of XH.YL
adde r8, r8, r0
li r7, 0
addze r7, r7
mullw r0, r3, r5 # r0 = low half of XH.YH
addc r8, r8, r0
mulhwu r0, r3, r5 # r0 = high half of XH.YH
adde r7, r7, r0
# Here r7:r8 contains the high 64 bits of the unsigned product.
# Now, test signs and subtract if needed
srawi r0, r3, 31 # r0 = -1 if X < 0, r0 = 0 if X >= 0
srawi r9, r5, 31 # r9 = -1 if Y < 0, r9 = 0 if Y >= 0
and r3, r3, r9 # set X = 0 if Y >= 0
and r4, r4, r9
and r5, r5, r0 # set Y = 0 if X >= 0
and r6, r6, r0
subfc r8, r4, r8 # subtract X
subfe r7, r3, r7
subfc r4, r6, r8 # subtract Y
subfe r3, r5, r7
blr
.type __compcert_i64_smulh, @function
.size __compcert_i64_smulh, .-__compcert_i64_smulh
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