| /* Copyright (c) 2002, Reiner Patommel |
| 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: asin.S 2191 2010-11-05 13:45:57Z arcanum $ */ |
| |
| /* float asin (float A); |
| The asin() function returns the arc sine in radians and the value is |
| mathematically defined to be between -PI/2 and PI/2 (inclusive). |
| */ |
| |
| |
| #if !defined(__AVR_TINY__) |
| |
| #include "fp32def.h" |
| #include "asmdef.h" |
| |
| #define X2SMALL 0x3e78ffff |
| #define HI40_PI_2 0x3fc90fda /* high 4 bytes of Pi/2 */ |
| #define LO40_PI_2 0xa2 /* lowest byte of Pi/2 */ |
| |
| ENTRY asin |
| ; save A sign |
| push rA3 |
| ; A = fabs(A) |
| andi rA3, 0x7f |
| ; is A too small ? |
| ldi ZL, hhi8(X2SMALL + 1) |
| cpi rA2, hlo8(X2SMALL + 1) |
| cpc rA3, ZL |
| brsh 1f |
| ; for small x |
| ldi ZL, lo8 (.L_table) |
| ldi ZH, hi8 (.L_table) |
| rcall _U(__fp_powsodd) |
| rjmp 2f |
| ; arcsin(x) = Pi/2 - arccos(x) |
| 1: rcall _U(__fp_arccos) |
| subi rA3, 0x80 |
| ldi rBE, LO40_PI_2 |
| ldi rB0, lo8(HI40_PI_2) |
| ldi rB1, hi8(HI40_PI_2) |
| ldi rB2, hlo8(HI40_PI_2) |
| ldi rB3, hhi8(HI40_PI_2) |
| rcall _U(__addsf3x) |
| rcall _U(__fp_round) |
| ; restore sign |
| 2: pop r0 |
| sbrc r0, 7 |
| subi rA3, 0x80 |
| ret |
| ENDFUNC |
| |
| PGM_SECTION |
| .L_table: |
| .byte 3 |
| .byte 0x6e,0xdb,0x36,0x3d ; 15/336 |
| .byte 0x9a,0x99,0x99,0x99,0x3d ; 3/40 |
| .byte 0xab,0xaa,0xaa,0x2a,0x3e ; 1/6 |
| .byte 0x00,0x00,0x00,0x80,0x3f ; 1 |
| .end |
| |
| #endif /* !defined(__AVR_TINY__) */ |