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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.
#include "sysdeps.h"
@@@ Conversion from double float to signed 64-bit integer
FUNCTION(__i64_dtos)
#ifndef VARIANT_eabi
vmov r0, r1, d0
#endif
ASR r12, r1, #31 @ save sign of result in r12
@ extract unbiased exponent ((HI & 0x7FF00000) >> 20) - (1023 + 52) in r2
@ note: 1023 + 52 = 1075 = 1024 + 51
@ note: (HI & 0x7FF00000) >> 20 = (HI << 1) >> 21
LSL r2, r1, #1
LSR r2, r2, #21
SUB r2, r2, #51
SUB r2, r2, #1024
@ check range of exponent
cmn r2, #52 @ if EXP < -52, |double| is < 1.0
blt 1f
cmp r2, #11 @ if EXP >= 63 - 52, |double| is >= 2^63
bge 2f
@ extract true mantissa
BIC r1, r1, #0xFF000000
BIC r1, r1, #0x00F00000 @ HI &= ~0xFFF00000
ORR r1, r1, #0x00100000 @ HI |= 0x00100000
@ shift it appropriately
cmp r2, #0
blt 3f
@ EXP >= 0: shift left by EXP. Note that EXP < 12
rsb r3, r2, #32 @ r3 = 32 - amount
LSL r1, r1, r2
LSR r3, r0, r3
ORR r1, r1, r3
LSL r0, r0, r2
b 4f
@ EXP < 0: shift right by -EXP. Note that -EXP <= 52 but can be >= 32
3: RSB r2, r2, #0 @ r2 = -EXP = shift amount
RSB r3, r2, #32 @ r3 = 32 - amount
LSR r0, r0, r2
LSL r3, r1, r3
ORR r0, r0, r3
SUB r3, r2, #32 @ r3 = amount - 32 (see i64_shr.s)
LSR r3, r1, r3
ORR r0, r0, r3
LSR r1, r1, r2
@ apply sign to result
4: EOR r0, r0, r12
EOR r1, r1, r12
subs r0, r0, r12
sbc r1, r1, r12
bx lr
@ special cases
1: MOV r0, #0 @ result is 0
MOV r1, #0
bx lr
2: cmp r12, #0
blt 6f
mvn r0, #0 @ result is 0x7F....FF (MAX_SINT)
LSR r1, r0, #1
bx lr
6: MOV r0, #0 @ result is 0x80....00 (MIN_SINT)
MOV r1, #0x80000000
bx lr
ENDFUNCTION(__i64_dtos)
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