projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| 925e4449 | 1 | # Copyright (c) 1985 Regents of the University of California. |
| fe5be67b KB |
2 | # All rights reserved. |
| 3 | # | |
| 2bc65d90 | 4 | # %sccs.include.redist.sh% |
| fe5be67b | 5 | # |
| 2bc65d90 | 6 | # @(#)tan.s 5.4 (Berkeley) %G% |
| 925e4449 | 7 | # |
| 7c0a3811 GK |
8 | .data |
| 9 | .align 2 | |
| 10 | _sccsid: | |
| 2bc65d90 | 11 | .asciz "@(#)tan.s 1.1 (Berkeley) 8/21/85; 5.4 (ucb.elefunt) %G%" |
| 925e4449 ZAL |
12 | |
| 13 | # This is the implementation of Peter Tang's double precision | |
| 14 | # tangent for the VAX using Bob Corbett's argument reduction. | |
| 15 | # | |
| 16 | # Notes: | |
| 17 | # under 1,024,000 random arguments testing on [0,2*pi] | |
| 18 | # tan() observed maximum error = 2.15 ulps | |
| 19 | # | |
| 20 | # double tan(arg) | |
| 21 | # double arg; | |
| 22 | # method: true range reduction to [-pi/4,pi/4], P. Tang & B. Corbett | |
| 23 | # S. McDonald, April 4, 1985 | |
| 24 | # | |
| 25 | .globl _tan | |
| 26 | .text | |
| 27 | .align 1 | |
| 28 | ||
| 29 | _tan: .word 0xffc # save r2-r11 | |
| 30 | movq 4(ap),r0 | |
| 31 | bicw3 $0x807f,r0,r2 | |
| 32 | beql 1f # if x is zero or reserved operand then return x | |
| 33 | # | |
| 34 | # Save the PSL's IV & FU bits on the stack. | |
| 35 | # | |
| 36 | movpsl r2 | |
| 37 | bicw3 $0xff9f,r2,-(sp) | |
| 38 | # | |
| 39 | # Clear the IV & FU bits. | |
| 40 | # | |
| 41 | bicpsw $0x0060 | |
| 42 | jsb libm$argred | |
| 43 | # | |
| 44 | # At this point, | |
| 45 | # r0 contains the quadrant number, 0, 1, 2, or 3; | |
| 46 | # r2/r1 contains the reduced argument as a D-format number; | |
| 47 | # r3 contains a F-format extension to the reduced argument; | |
| 48 | # | |
| 49 | # Save r3/r0 so that we can call cosine after calling sine. | |
| 50 | # | |
| 51 | movq r2,-(sp) | |
| 52 | movq r0,-(sp) | |
| 53 | # | |
| 54 | # Call sine. r4 = 0 implies sine. | |
| 55 | # | |
| 56 | movl $0,r4 | |
| 57 | jsb libm$sincos | |
| 58 | # | |
| 59 | # Save sin(x) in r11/r10 . | |
| 60 | # | |
| 61 | movd r0,r10 | |
| 62 | # | |
| 63 | # Call cosine. r4 = 1 implies cosine. | |
| 64 | # | |
| 65 | movq (sp)+,r0 | |
| 66 | movq (sp)+,r2 | |
| 67 | movl $1,r4 | |
| 68 | jsb libm$sincos | |
| 69 | divd3 r0,r10,r0 | |
| 70 | bispsw (sp)+ | |
| 71 | 1: ret |