xref: /csrg-svn/sys/sparc/fpu/fpu_arith.h (revision 63319)
155111Storek /*
2*63319Sbostic  * Copyright (c) 1992, 1993
3*63319Sbostic  *	The Regents of the University of California.  All rights reserved.
455111Storek  *
555111Storek  * This software was developed by the Computer Systems Engineering group
655111Storek  * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
755111Storek  * contributed to Berkeley.
855111Storek  *
955500Sbostic  * All advertising materials mentioning features or use of this software
1055500Sbostic  * must display the following acknowledgement:
1155500Sbostic  *	This product includes software developed by the University of
1259195Storek  *	California, Lawrence Berkeley Laboratory.
1355500Sbostic  *
1455111Storek  * %sccs.include.redist.c%
1555111Storek  *
16*63319Sbostic  *	@(#)fpu_arith.h	8.1 (Berkeley) 06/11/93
1755111Storek  *
1859195Storek  * from: $Header: fpu_arith.h,v 1.3 92/11/26 01:30:50 torek Exp $
1955111Storek  */
2055111Storek 
2155111Storek /*
2255111Storek  * Extended-precision arithmetic.
2355111Storek  *
2455111Storek  * We hold the notion of a `carry register', which may or may not be a
2555111Storek  * machine carry bit or register.  On the SPARC, it is just the machine's
2655111Storek  * carry bit.
2755111Storek  *
2855111Storek  * In the worst case, you can compute the carry from x+y as
2955111Storek  *	(unsigned)(x + y) < (unsigned)x
3055111Storek  * and from x+y+c as
3155111Storek  *	((unsigned)(x + y + c) <= (unsigned)x && (y|c) != 0)
3255111Storek  * for example.
3355111Storek  */
3455111Storek 
3555111Storek /* set up for extended-precision arithemtic */
3655111Storek #define	FPU_DECL_CARRY
3755111Storek 
3855111Storek /*
3955111Storek  * We have three kinds of add:
4055111Storek  *	add with carry:					  r = x + y + c
4155111Storek  *	add (ignoring current carry) and set carry:	c'r = x + y + 0
4255111Storek  *	add with carry and set carry:			c'r = x + y + c
4355111Storek  * The macros use `C' for `use carry' and `S' for `set carry'.
4455111Storek  * Note that the state of the carry is undefined after ADDC and SUBC,
4555111Storek  * so if all you have for these is `add with carry and set carry',
4655111Storek  * that is OK.
4755111Storek  *
4855111Storek  * The same goes for subtract, except that we compute x - y - c.
4955111Storek  *
5055111Storek  * Finally, we have a way to get the carry into a `regular' variable,
5155111Storek  * or set it from a value.  SET_CARRY turns 0 into no-carry, nonzero
5255111Storek  * into carry; GET_CARRY sets its argument to 0 or 1.
5355111Storek  */
5455111Storek #define	FPU_ADDC(r, x, y) \
5555111Storek 	asm volatile("addx %1,%2,%0" : "=r"(r) : "r"(x), "r"(y))
5655111Storek #define	FPU_ADDS(r, x, y) \
5755111Storek 	asm volatile("addcc %1,%2,%0" : "=r"(r) : "r"(x), "r"(y))
5855111Storek #define	FPU_ADDCS(r, x, y) \
5955111Storek 	asm volatile("addxcc %1,%2,%0" : "=r"(r) : "r"(x), "r"(y))
6055111Storek #define	FPU_SUBC(r, x, y) \
6155111Storek 	asm volatile("subx %1,%2,%0" : "=r"(r) : "r"(x), "r"(y))
6255111Storek #define	FPU_SUBS(r, x, y) \
6355111Storek 	asm volatile("subcc %1,%2,%0" : "=r"(r) : "r"(x), "r"(y))
6455111Storek #define	FPU_SUBCS(r, x, y) \
6555111Storek 	asm volatile("subxcc %1,%2,%0" : "=r"(r) : "r"(x), "r"(y))
6655111Storek 
6755111Storek #define	FPU_GET_CARRY(r) asm volatile("addx %%g0,%%g0,%0" : "=r"(r))
6855111Storek #define	FPU_SET_CARRY(v) asm volatile("addcc %0,-1,%%g0" : : "r"(v))
6955111Storek 
7055111Storek #define	FPU_SHL1_BY_ADD	/* shift left 1 faster by ADDC than (a<<1)|(b>>31) */
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