| /* 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: tan.S 1174 2007-01-14 15:13:54Z dmix $ */ |
| |
| #include "fp32def.h" |
| #include "asmdef.h" |
| |
| /* float tan (float A); |
| The tan() function returns the tangent of A, where A is given |
| in radians. |
| */ |
| |
| /* Calculation: |
| 0 <= x <= Pi/4 --> tan(x) fmod |
| Pi/4 < x < Pi/2 --> 1/tan(Pi/2-x) fmod, Pi/2-x, 1/x |
| Pi/2 <= x <= 3*Pi/4 --> -1/tan(x-Pi/2) fmod, 1/x, -x |
| 3*Pi/4 < x < Pi --> -tan(Pi-x) fmod, Pi/2-x, -x |
| */ |
| #define HI40_PIO4 0x3F490FDA /* (flt40_t) Pi/4 */ |
| #define LO40_PIO4 0xA2 /* --"-- */ |
| #define HI40_PIO2 0x3FC90FDA /* (flt40_t) Pi/2 */ |
| #define LO40_PIO2 0xA2 /* --"-- */ |
| |
| #define rsign YH |
| |
| ENTRY tan |
| ; save sign |
| push rsign |
| mov rsign, rA3 |
| ; fmod by Pi/2 |
| rcall _U(__fp_rempio2) |
| ; save perion number |
| lsr ZL |
| ror rsign |
| ; is A <= Pi/4 ? |
| #if LO40_PIO4 == 0xFF /* HI40_PIO4: increment is not needed */ |
| # error |
| #endif |
| ldi rB0, lo8(HI40_PIO4) |
| ldi rB1, hi8(HI40_PIO4) |
| ldi rB2, hlo8(HI40_PIO4) |
| ldi rB3, hhi8(HI40_PIO4) |
| cpi rAE, LO40_PIO4 + 1 |
| cpc rA0, rB0 |
| cpc rA1, rB1 |
| cpc rA2, rB2 |
| cpc rA3, rB3 |
| ror rsign ; save comparison result |
| brmi 1f ; N == C flag after comparison |
| ; for A > Pi/4: tan(A) == 1/tan(Pi/2 - A) |
| #if (HI40_PIO4 ^ HI40_PIO2) & 0xFF00FFFF /* 'ldi' optimization */ |
| # error |
| #endif |
| ldi rBE, LO40_PIO2 |
| ldi rB2, hlo8(HI40_PIO2) |
| ori rA3, 0x80 |
| rcall _U(__addsf3x) |
| rcall _U(__fp_round) |
| ; calculate tan(A) for 0 <= A <= Pi/4 |
| 1: ldi ZL, lo8(.L_table) |
| ldi ZH, hi8(.L_table) |
| rcall _U(__fp_powsodd) |
| ; correct result |
| lsl rsign |
| brvs 2f |
| rcall _U(inverse) |
| 2: lsl rsign |
| brvc 3f |
| subi rA3, 0x80 |
| 3: pop rsign |
| ret |
| ENDFUNC |
| |
| PGM_SECTION |
| .L_table: |
| .byte 6 |
| .byte 0x64,0xec,0x1b,0x3c ; 0.0095168091 |
| .byte 0x04,0xbc,0x16,0x3e,0x3b ; 0.0029005250 |
| .byte 0xe5,0xb9,0x3c,0xc9,0x3c ; 0.0245650893 |
| .byte 0x37,0xc2,0x9e,0x5a,0x3d ; 0.0533740603 |
| .byte 0x66,0x04,0x98,0x08,0x3e ; 0.1333923995 |
| .byte 0xea,0x69,0xaa,0xaa,0x3e ; 0.3333314036 |
| .byte 0x00,0x00,0x00,0x80,0x3f ; 1.0000000000 |
| .end |
