UNIX 6th Ed. - /usr/source/s3/atan.s

   1: ldfps = 170100^tst
   2: stfps = 170200^tst
   3: /
   4: .globl  atan, _atan
   5: .globl  atan2, _atan2
   6: /
   7: /	floating-point arctangent
   8: /
   9: /	atan replaces the value in fr0 by its arctangent
  10: /	in the range [-pi/2,pi/2].
  11: /
  12: /	atan2 places in fr0 the arctangent of fr0/fr1
  13: /	in the range [-pi,pi].
  14: /
  15: /	there are no error exits
  16: /
  17: /	coefficients are #5076 from Hart & Cheney.
  18: /
  19: /
  20: 
  21: _atan:
  22:         mov     r5,-(sp)
  23:         mov     sp,r5
  24:         movf    4(r5),fr0
  25:         jsr     pc,atan
  26:         br      1f
  27: 
  28: _atan2:
  29:         mov     r5,-(sp)
  30:         mov     sp,r5
  31:         movf    4(r5),fr0
  32:         movf    12.(r5),fr1
  33:         jsr     pc,atan2
  34: 1:
  35:         mov     (sp)+,r5
  36:         rts     pc
  37: atan:
  38:         jsr     r0,save
  39:         tstf    fr0
  40:         cfcc
  41:         blt     1f
  42:         jsr     pc,satan
  43:         br      ret
  44: 1:
  45:         negf    fr0
  46:         jsr     pc,satan
  47:         negf    fr0
  48:         br      ret
  49: /
  50: atan2:
  51:         jsr     r0,save
  52:         clr     -(sp)
  53:         tstf    fr0
  54:         cfcc
  55:         bge     1f
  56:         inc     (sp)
  57:         negf    fr0
  58: 1:
  59:         tstf    fr1
  60:         cfcc
  61:         beq     2f
  62:         bgt     1f
  63:         add     $2,(sp)
  64:         negf    fr1
  65: 1:
  66:         divf    fr1,fr0
  67:         jsr     pc,satan
  68:         br      1f
  69: 2:
  70:         movf    pi2,fr0
  71: 1:
  72:         bit     $2,(sp)
  73:         beq     1f
  74:         negf    fr0
  75:         addf    pi2,fr0
  76:         addf    pi2,fr0
  77: 1:
  78:         bit     $1,(sp)+
  79:         beq     1f
  80:         negf    fr0
  81: 1:
  82: 
  83: ret:
  84:         ldfps   (sp)+
  85:         movf    (sp)+,fr3
  86:         movf    (sp)+,fr2
  87:         movf    (sp)+,fr1
  88:         mov     (sp)+,r0
  89:         rts     pc
  90: 
  91: save:
  92:         movf    fr1,-(sp)
  93:         movf    fr2,-(sp)
  94:         movf    fr3,-(sp)
  95:         stfps   -(sp)
  96:         ldfps   $40200          / DP, no interrupt
  97:         jmp     (r0)
  98: 
  99: satan:
 100:         cmpf    sq2m1,fr0
 101:         cfcc
 102:         bge     arctan
 103:         cmpf    sq2p1,fr0
 104:         cfcc
 105:         bgt     1f
 106:         movf    one,fr1
 107:         divf    fr0,fr1
 108:         movf    fr1,fr0
 109:         jsr     pc,arctan
 110:         negf    fr0
 111:         addf    pi2,fr0
 112:         rts     pc
 113: 1:
 114:         movf    fr0,fr1
 115:         subf    one,fr0
 116:         addf    one,fr1
 117:         divf    fr1,fr0
 118:         jsr     pc,arctan
 119:         addf    pi4,fr0
 120:         rts     pc
 121: arctan:
 122:         mov     $p4p,r0
 123:         mov     $4,-(sp)
 124:         movf    fr0,fr3
 125:         mulf    fr3,fr3
 126:         movf    *(r0)+,fr1
 127: 1:
 128:         mulf    fr3,fr1
 129:         addf    *(r0)+,fr1
 130:         dec     (sp)
 131:         bne     1b
 132:         mov     $4,(sp)
 133:         movf    fr3,fr2
 134:         br      2f
 135: 1:
 136:         mulf    fr3,fr2
 137: 2:
 138:         addf    *(r0)+,fr2
 139:         dec     (sp)
 140:         bne     1b
 141:         tst     (sp)+
 142:         divf    fr2,fr1
 143:         mulf    fr1,fr0
 144:         rts     pc
 145: 
 146: .data
 147: 
 148: p4p:
 149:         p4;p3;p2;p1;p0
 150:         q3;q2;q1;p0
 151: 
 152: one:    40200;0;0;0
 153: pi2:    40311;7732;121041;64302
 154: pi4:    40111;7732;121041;64302
 155: 
 156: sq2p1:  40432
 157:         101171
 158:         114774
 159:         167461
 160: 
 161: sq2m1:  37724
 162:         11714
 163:         147747
 164:         74621
 165: 
 166: p4:     37442
 167:         145026
 168:         75504
 169:         15621
 170: p3:     40725
 171:         21566
 172:         115517
 173:         50305
 174: p2:     41443
 175:         160206
 176:         172714
 177:         25441
 178: p1:     41632
 179:         172223
 180:         76027
 181:         56645
 182: p0:     41462
 183:         25125
 184:         6152
 185:         126064
 186: q3:     41170
 187:         10112
 188:         141724
 189:         64324
 190: q2:     41573
 191:         53776
 192:         25372
 193:         71522
 194: q1:     41670
 195:         123114
 196:         51576
 197:         75020
 198: 
 199: /	one = 1.00000 00000 00000 00000 d0
 200: /	sq2p1=2.41421 35623 73095 04880 d0
 201: /	sq2m1= .41421 35623 73095 04880 d0
 202: /	pi2 = 1.57079 63267 94896 61923  d0
 203: /	p4 = .15897 40288 48230 7048 d0
 204: /	p3 = .66605 79017 00926 2658 d1
 205: /	p2 = .40969 26483 21022 5637 d2
 206: /	p1 = .77477 68771 92042 0862 d2
 207: /	p0 = .44541 34005 92906 8032 d2
 208: /	q4 = .10000 00000 00000 0000 d1
 209: /	q3 = .15503 97755 14219 8753 d2
 210: /	q2 = .62835 93051 10323 7683 d2
 211: /	q1 = .92324 80107 23009 7484 d2
 212: /	q0 = .44541 34005 92906 8044 d2

Defined functions

Defined variables