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/* Copyright (c) 2002 Michael Stumpf <mistumpf@de.pepperl-fuchs.com>
Copyright (c) 2006 Dmitry Xmelkov
All rights reserved.
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 copyright holders nor the names of
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 THE COPYRIGHT OWNER OR CONTRIBUTORS 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. */
/* $Id: fp_mintl.S,v 1.1 2007/01/14 14:53:45 dmix Exp $ */
#include "fp32def.h"
#include "asmdef.h"
/* float __fp_mintl (<non-standart>);
Normalize value by shifting to left (only left) and merge parts of
float value. Mainly, this function is intended for integral values,
as a last stage of functions floor(), floatsisf(). Its functionality
is very restricted: no subnormals, no rounding, no Inf/NaN.
Input:
T - sign
rA3 - exponent
rA2.rA1.rA0 - mantissa
Output:
rA3.rA2.rA1.rA0 - float value
Notes:
* Underflow of exponent is NOT checked: result would undefined.
* In zero case mantissa must be 0.
* Sign bit is set in any case. -0.0 is possible.
* Shifts are optimized for speed.
*/
ENTRY __fp_mintl
tst rA2
brne .L_bm
tst rA1
breq 1f
; mantissa is 0x00XXXX
subi rA3, 8
or rA2, rA1 ; to obtain N flag (rA2 was 0)
mov rA1, rA0
rjmp .L_a0
; mantissa is 0x0000XX
1: tst rA0
brne 2f
clr rA3
rjmp .L_sign
; low mantissa byte != 0
2: subi rA3, 16
or rA2, rA0 ; to obtain N flag (rA2 was 0)
ldi rA1, 0
.L_a0: ldi rA0, 0
.L_bm: brmi .L_pack ; N flag is from rA2
; shift to left (1..7 positions)
.Loop: dec rA3
lsl rA0
rol rA1
rol rA2
brpl .Loop
.L_pack:
lsl rA2
lsr rA3
ror rA2
.L_sign:
bld rA3, 7 ; sign
ret
ENDFUNC
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