85 lines
2.3 KiB
ArmAsm
85 lines
2.3 KiB
ArmAsm
# Copyright (c) 1985 Regents of the University of California.
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# All rights reserved.
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#
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# Redistribution and use in source and binary forms are permitted provided
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# that: (1) source distributions retain this entire copyright notice and
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# comment, and (2) distributions including binaries display the following
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# acknowledgement: ``This product includes software developed by the
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# University of California, Berkeley and its contributors'' in the
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# documentation or other materials provided with the distribution and in
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# all advertising materials mentioning features or use of this software.
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# Neither the name of the University nor the names of its contributors may
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# be used to endorse or promote products derived from this software without
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# specific prior written permission.
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# THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
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# WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
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# MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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LAR PURPOSE.
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#
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# @(#)tan.s 5.4 (Berkeley) 10/9/90
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#
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.data
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.align 2
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_sccsid:
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.asciz "@(#)tan.s 1.1 (Berkeley) 8/21/85; 5.4 (ucb.elefunt) 10/9/90"
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# This is the implementation of Peter Tang's double precision
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# tangent for the VAX using Bob Corbett's argument reduction.
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#
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# Notes:
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# under 1,024,000 random arguments testing on [0,2*pi]
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# tan() observed maximum error = 2.15 ulps
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#
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# double tan(arg)
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# double arg;
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# method: true range reduction to [-pi/4,pi/4], P. Tang & B. Corbett
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# S. McDonald, April 4, 1985
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#
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.globl _tan
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.text
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.align 1
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_tan: .word 0xffc # save r2-r11
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movq 4(ap),r0
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bicw3 $0x807f,r0,r2
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beql 1f # if x is zero or reserved operand then return x
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#
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# Save the PSL's IV & FU bits on the stack.
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#
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movpsl r2
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bicw3 $0xff9f,r2,-(sp)
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#
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# Clear the IV & FU bits.
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#
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bicpsw $0x0060
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jsb libm$argred
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#
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# At this point,
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# r0 contains the quadrant number, 0, 1, 2, or 3;
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# r2/r1 contains the reduced argument as a D-format number;
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# r3 contains a F-format extension to the reduced argument;
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#
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# Save r3/r0 so that we can call cosine after calling sine.
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#
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movq r2,-(sp)
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movq r0,-(sp)
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#
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# Call sine. r4 = 0 implies sine.
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#
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movl $0,r4
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jsb libm$sincos
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#
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# Save sin(x) in r11/r10 .
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#
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movd r0,r10
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#
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# Call cosine. r4 = 1 implies cosine.
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#
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movq (sp)+,r0
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movq (sp)+,r2
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movl $1,r4
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jsb libm$sincos
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divd3 r0,r10,r0
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bispsw (sp)+
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1: ret
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