diff options
Diffstat (limited to 'runtime/powerpc/i64_udivmod.s')
| -rw-r--r-- | runtime/powerpc/i64_udivmod.s | 95 |
1 files changed, 95 insertions, 0 deletions
diff --git a/runtime/powerpc/i64_udivmod.s b/runtime/powerpc/i64_udivmod.s new file mode 100644 index 0000000..892e9a0 --- /dev/null +++ b/runtime/powerpc/i64_udivmod.s @@ -0,0 +1,95 @@ +# ***************************************************************** +# +# 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 |