| /* 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: ldexp.S 2191 2010-11-05 13:45:57Z arcanum $ */ |
| |
| #if !defined(__AVR_TINY__) |
| |
| #include "fp32def.h" |
| #include "asmdef.h" |
| |
| /* double ldexp (double x, int exp) |
| The ldexp() function returns the result of multiplying the |
| floating-point number x by 2 raised to the power exp. |
| */ |
| #define exp_lo r20 |
| #define exp_hi r21 |
| |
| FUNCTION ldexp |
| |
| .L_inf: rjmp _U(__fp_inf) |
| .L_pk: rjmp _U(__fp_mpack) |
| |
| ENTRY ldexp |
| rcall _U(__fp_splitA) |
| brcs .L_pk ; as is |
| tst rA3 |
| breq .L_pk ; ldexp(0,*) is always 0 |
| |
| .ifnc rB3, exp_hi |
| .err ; rB3 and exp_hi are different |
| .endif |
| add rA3, exp_lo ; rB3.rA3 := new exponent |
| adc rB3, r1 |
| brvs .L_inf ; overflow is possible for exp > 0 only |
| |
| ; check exponent for minus and zero |
| subi rA3, lo8(1) |
| sbci rB3, hi8(1) |
| brlt 5f ; denormalization is needed |
| breq .L_pack ; normalization is impossible |
| 1: tst rA2 |
| brmi 2f |
| lsl rA0 |
| rol rA1 |
| rol rA2 |
| subi rA3, lo8(1) |
| sbci rB3, hi8(1) |
| brne 1b ; C == 0, Z == 0 |
| ; check to overflow |
| 2: cpi rA3, 254 |
| cpc rB3, r1 |
| brge .L_inf |
| .L_pack: |
| lsl rA2 |
| adc rA3, r1 ; restore exponent for normal numbers |
| lsr rA3 |
| ror rA2 |
| bld rA3, 7 ; sign |
| ret |
| ; exponent <= 0 |
| 5: cpi rB3, hi8(-24) |
| brlt .L_zero |
| cpi rA3, lo8(-24) |
| brlt .L_zero |
| ; denormalize A |
| clr rAE |
| 6: lsr rA2 |
| ror rA1 |
| ror rA0 |
| ror rAE |
| brcc 7f |
| ori rAE, 1 |
| 7: inc rA3 |
| brne 6b |
| .L_round: |
| lsl rAE |
| brcc .L_pack |
| brne 4f |
| sbrs rA0, 0 |
| rjmp .L_pack |
| 4: subi rA0, -1 |
| sbci rA1, -1 |
| sbci rA2, -1 |
| sbci rA3, -1 |
| rjmp .L_pack |
| .L_zero: |
| rjmp _U(__fp_szero) |
| ENDFUNC |
| |
| #endif /* !defined(__AVR_TINY__) */ |
