| /* 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: frexp.S 2191 2010-11-05 13:45:57Z arcanum $ */ |
| |
| #if !defined(__AVR_TINY__) |
| |
| #include "fp32def.h" |
| #include "asmdef.h" |
| |
| /* float frexp (float A, int *pexp); |
| The frexp() function is used to split the number A into a normalized |
| fraction and an exponent which is stored by pexp. |
| |
| Return: |
| If A is a normal float point number, the frexp() function returns the |
| value v, such that v has a magnitude in the interval [1/2, 1) or zero, |
| and A equals v times 2 raised to the power *pexp. If A is zero, both |
| parts of the result are zero. If A is not a finite number, the frexp() |
| returns A as is and stores 0 by pexp. |
| |
| Note: |
| This implementation permits a zero pointer as a directive to skip |
| a storing the exponent. |
| */ |
| |
| #define pexp_lo r20 |
| |
| ENTRY frexp |
| |
| X_movw ZL, pexp_lo |
| |
| ; Write 0 for next cases: Zero, Inf or NaN. |
| #if defined(__AVR_XMEGA__) && __AVR_XMEGA__ |
| adiw ZL, 0 |
| breq 1f |
| #endif |
| st Z, r1 |
| std Z+1, r1 |
| 1: |
| rcall _U(__fp_splitA) |
| brcs .L_nf ; return the same value |
| tst rA3 |
| breq 3f |
| subi rA3, 126 |
| sbc rB3, rB3 |
| |
| sbrs rA2, 7 |
| rcall _U(__fp_norm2) |
| |
| #if defined(__AVR_XMEGA__) && __AVR_XMEGA__ |
| adiw ZL, 0 |
| breq 2f |
| st Z, rA3 |
| std Z+1, rB3 |
| 2: |
| #else |
| ; NULL is a legal address. Instead to check Z==0, will simply |
| ; write and restore r1. |
| st Z, rA3 |
| std Z+1, rB3 |
| clr r1 ; protection to Z == 0 |
| #endif |
| |
| andi rA2, 0x7f |
| ldi rA3, 0x3f |
| |
| 3: bld rA3, 7 ; restore sign |
| ret |
| .L_nf: |
| rjmp _U(__fp_mpack) |
| ENDFUNC |
| |
| #endif /* !defined(__AVR_TINY__) */ |