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| Commit | Line | Data |
|---|---|---|
| 7049871b TL |
1 | # double atan(arg1); -pi/2 < atan < pi/2 |
| 2 | #double atan2(arg1,arg2); -pi< atan2<pi | |
| 3 | #double arg1,arg2 | |
| 4 | #method: range reduction to [sqrt(2)-1,sqrt(2)+1] | |
| 5 | # followed by Hart&Cheney ARCTN 5076 D=17.55 | |
| 6 | # J. F. Jarvis August 8, 1978 | |
| 7 | .globl _atan | |
| 8 | .globl _atan2 | |
| 9 | .text | |
| 10 | .align 1 | |
| 11 | _atan: | |
| 12 | .word 0x03c0 | |
| 13 | movd 4(ap),r0 | |
| 14 | jgtr a1 | |
| 15 | mnegd r0,r0 # atan(arg1), arg1<0 | |
| 16 | bsbb satan | |
| 17 | mnegd r0,r0 | |
| 18 | ret | |
| 19 | a1: bsbb satan # atan(arg1), arg1>=0 | |
| 20 | ret | |
| 21 | # | |
| 22 | .align 1 | |
| 23 | _atan2: | |
| 24 | .word 0x03c0 | |
| 25 | movd 4(ap),r0 # atan(arg1/arg2) | |
| 26 | movd 12(ap),r2 | |
| 27 | addd3 r0,r2,r4 | |
| 28 | cmpd r0,r4 | |
| 29 | jneq b1 | |
| 30 | tstd r0 | |
| 31 | jgeq b2 | |
| 32 | mnegd pio2,r0 | |
| 33 | ret | |
| 34 | b2: movd pio2,r0 | |
| 35 | ret | |
| 36 | # | |
| 37 | b1: tstd r2 | |
| 38 | jgeq b3 | |
| 39 | divd2 r2,r0 | |
| 40 | jleq b4 | |
| 41 | bsbb satan # arg1<0, arg2<0 | |
| 42 | subd2 pi,r0 | |
| 43 | ret | |
| 44 | b4: mnegd r0,r0 # arg1>0, arg2<0 | |
| 45 | bsbb satan | |
| 46 | subd3 r0,pi,r0 | |
| 47 | ret | |
| 48 | # | |
| 49 | b3: divd2 r2,r0 | |
| 50 | jleq b5 | |
| 51 | bsbb satan # arg1>0, arg2>0 | |
| 52 | ret | |
| 53 | b5: mnegd r0,r0 # arg1<0, arg2>0 | |
| 54 | bsbb satan | |
| 55 | mnegd r0,r0 | |
| 56 | ret | |
| 57 | # | |
| 58 | .globl satan | |
| 59 | satan: # range reduction on positive arg(r0) | |
| 60 | cmpd r0,sq2m1 | |
| 61 | jgeq c1 | |
| 62 | bsbb xatan | |
| 63 | rsb | |
| 64 | c1: cmpd r0,sq2p1 | |
| 65 | jleq c2 | |
| 66 | divd3 r0,$0d1.0e+0,r0 | |
| 67 | bsbb xatan | |
| 68 | subd3 r0,pio2,r0 | |
| 69 | rsb | |
| 70 | c2: addd3 $0d1.0e+0,r0,r2 | |
| 71 | subd2 $0d1.0e+0,r0 | |
| 72 | divd2 r2,r0 | |
| 73 | bsbb xatan | |
| 74 | addd2 pio4,r0 | |
| 75 | rsb | |
| 76 | # | |
| 77 | xatan: # compute arctan(r0) for:sqrt(2)-1<r0<sqrt(2)+1 | |
| 78 | # Hart&Cheney ARCTN 5076 is evaluated | |
| 79 | movd r0,r8 | |
| 80 | muld3 r0,r0,r6 | |
| 81 | polyd r6,$4,pcoef | |
| 82 | muld2 r0,r8 | |
| 83 | polyd r6,$4,qcoef | |
| 84 | divd3 r0,r8,r0 | |
| 85 | rsb | |
| 86 | .data | |
| 87 | .align 3 | |
| 88 | pcoef: | |
| 89 | .double 0d0.1589740288482307048e+0 | |
| 90 | .double 0d0.66605790170092626575e+1 | |
| 91 | .double 0d0.40969264832102256374e+2 | |
| 92 | .double 0d0.77477687719204208616e+2 | |
| 93 | .double 0d0.44541340059290680319e+2 | |
| 94 | qcoef: | |
| 95 | .double 0d1.0e+0 | |
| 96 | .double 0d0.15503977551421987525e+2 | |
| 97 | .double 0d0.62835930511032376833e+2 | |
| 98 | .double 0d0.92324801072300974840e+2 | |
| 99 | .double 0d0.44541340059290680444e+2 | |
| 100 | pio4: .double 0d0.78539816339744830961e+0 | |
| 101 | pio2: .double 0d1.57079632679489661923e+0 | |
| 102 | sq2p1: .double 0d2.41421356237309504880e+0 | |
| 103 | sq2m1: .double 0d0.41421356237309504880e+0 | |
| 104 | pi: .double 0d3.14159265358979323846e+0 |