| /* 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: log.S 2191 2010-11-05 13:45:57Z arcanum $ */ |
| |
| #if !defined(__AVR_TINY__) |
| |
| #include "fp32def.h" |
| #include "asmdef.h" |
| |
| /* double log (double A) |
| The log() function returns the natural logarithm of A. |
| */ |
| |
| #define FL_M1 0xbf800000 /* -1.0 */ |
| #define LN_2 0x3f317218 /* ln(2.0) = 0.69314718 */ |
| |
| #define rC3 YH |
| #define rC2 YL /* adiw,sbiw are used */ |
| #define rC1 r17 |
| #define rC0 r16 |
| #define rCE r15 |
| |
| FUNCTION log |
| |
| .L_nf: brts .L_nan ; branch, if -Inf |
| rjmp _U(__fp_mpack) ; pass as is: NaN --> NaN, +Inf --> +Inf |
| .L_nan: rjmp _U(__fp_nan) |
| .L_min: set |
| rjmp _U(__fp_inf) |
| |
| ENTRY log |
| rcall _U(__fp_splitA) |
| brcs .L_nf ; !isfinite(A) |
| tst rA3 |
| breq .L_min ; -Inf |
| brts .L_nan ; log(negative) |
| |
| push rC3 |
| push rC2 |
| push rC1 |
| push rC0 |
| push rCE |
| ; normalize (if Subnormal) |
| mov rC2, rA3 ; place exponent to pair rC3.rC2 |
| clr rC3 |
| tst rA2 |
| brmi 2f |
| 1: sbiw rC2, 1 |
| lsl rA0 |
| rol rA1 |
| rol rA2 |
| brpl 1b |
| 2: |
| ; calculate log(1+x) for x: -0x0.20p+0 <= x < 0.E0p+0 |
| /* Different tables are used: |
| .L_tlow - for small values: -0x0.20p+0 <= x < + 0x0.18p+0 |
| .L_thigh - for others */ |
| ldi rB0, lo8(FL_M1) |
| ldi rB1, hi8(FL_M1) |
| ldi rB2, hlo8(FL_M1) |
| ldi rB3, hhi8(FL_M1) |
| ldi rA3, 0x3f |
| cpi rA2, 0x98 |
| brlo 3f |
| cpi rA2, 0xE0 |
| brlo 4f |
| adiw rC2, 1 |
| andi rA2, ~0x80 |
| 3: rcall _U(__addsf3) |
| ldi ZL, lo8(.L_tlow) |
| ldi ZH, hi8(.L_tlow) |
| rjmp 5f |
| 4: rcall _U(__addsf3) |
| ldi ZL, lo8(.L_thigh) |
| ldi ZH, hi8(.L_thigh) |
| 5: rcall _U(__fp_powser) |
| |
| X_movw rC0, rA0 |
| X_movw rA0, rC2 ; rA1.rA0 = exponent (possible negative) |
| X_movw rC2, rA2 |
| mov rCE, rAE |
| ; calculate log() of exponent |
| subi rA0, 127 ; 127 is exponent field of 1.0 |
| sbc rA1, r1 |
| asr rA1 |
| rol rA1 ; C = rA1 sign bit |
| sbc rA2, rA2 |
| sbc rA3, rA3 |
| rcall _U(__floatsisf) |
| ldi rB0, lo8(LN_2) |
| ldi rB1, hi8(LN_2) |
| ldi rB2, hlo8(LN_2) |
| ldi rB3, hhi8(LN_2) |
| rcall _U(__mulsf3x) |
| |
| mov rBE, rCE |
| X_movw rB0, rC0 |
| X_movw rB2, rC2 |
| |
| pop rCE |
| pop rC0 |
| pop rC1 |
| pop rC2 |
| pop rC3 |
| |
| rcall _U(__addsf3x) |
| rjmp _U(__fp_round) |
| ENDFUNC |
| |
| PGM_SECTION |
| |
| .L_tlow: ; __fp_powser() table for small values |
| .byte 8 |
| .byte 0x00,0x00,0x00,0xbe ; -0.1250000000 |
| .byte 0x92,0x24,0x49,0x12,0x3e ; 0.1428571429 |
| .byte 0xab,0xaa,0xaa,0x2a,0xbe ; -0.1666666667 |
| .byte 0xcd,0xcc,0xcc,0x4c,0x3e ; 0.2000000000 |
| .byte 0x00,0x00,0x00,0x80,0xbe ; -0.2500000000 |
| .byte 0xab,0xaa,0xaa,0xaa,0x3e ; 0.3333333333 |
| .byte 0x00,0x00,0x00,0x00,0xbf ; -0.5000000000 |
| .byte 0x00,0x00,0x00,0x80,0x3f ; 1.0000000000 |
| .byte 0x00,0x00,0x00,0x00,0x00 ; 0.0000000000 |
| |
| .L_thigh: ; __fp_powser() table for other values |
| .byte 8 |
| .byte 0x41,0x78,0xd3,0xbb ; -0.0064535442 |
| .byte 0x43,0x87,0xd1,0x13,0x3d ; 0.0360884937 |
| .byte 0x19,0x0e,0x3c,0xc3,0xbd ; -0.0953293897 |
| .byte 0x42,0x82,0xad,0x2b,0x3e ; 0.1676540711 |
| .byte 0x68,0xec,0x82,0x76,0xbe ; -0.2407338084 |
| .byte 0xd9,0x8f,0xe1,0xa9,0x3e ; 0.3317990258 |
| .byte 0x4c,0x80,0xef,0xff,0xbe ; -0.4998741238 |
| .byte 0x01,0xc4,0xff,0x7f,0x3f ; 0.9999964239 |
| .byte 0x00,0x00,0x00,0x00,0x00 ; 0.0000000000 |
| |
| .end |
| |
| #endif /* !defined(__AVR_TINY__) */ |
