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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. ARM version.
.text
@@@ Shift right unsigned
@ Note on ARM shifts: the shift amount is taken modulo 256.
@ If shift amount mod 256 >= 32, the shift produces 0.
@ Algorithm:
@ RL = (XL >> N) | (XH << (32-N) | (XH >> (N-32))
@ RH = XH >> N
@ If N = 0:
@ RL = XL | 0 | 0
@ RH = XH
@ If 1 <= N <= 31: 1 <= 32-N <= 31 and 255 <= N-32 mod 256 <= 255
@ RL = (XL >> N) | (XH >> (32-N) | 0
@ RH = XH >> N
@ If N = 32:
@ RL = 0 | XH | 0
@ RH = 0
@ If 33 <= N <= 63: 255 <= 32-N mod 256 <= 255 and 1 <= N-32 <= 31
@ RL = 0 | 0 | (XH >> (N-32))
@ RH = 0
.global __i64_shr
__i64_shr:
and r2, r2, #63 @ normalize amount to 0...63
rsb r3, r2, #32 @ r3 = 32 - amount
mov r0, r0, lsr r2
orr r0, r0, r1, lsl r3
sub r3, r2, #32 @ r3 = amount - 32
orr r0, r0, r1, lsr r3
mov r1, r1, lsr r2
bx lr
.type __i64_shr, %function
.size __i64_shr, . - __i64_shr
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