freebsd-skq/lib/libc/powerpcspe/gen/fpsetround.c
Justin Hibbits dc9b124d66 Create a new MACHINE_ARCH for Freescale PowerPC e500v2
Summary:
The Freescale e500v2 PowerPC core does not use a standard FPU.
Instead, it uses a Signal Processing Engine (SPE)--a DSP-style vector processor
unit, which doubles as a FPU.  The PowerPC SPE ABI is incompatible with the
stock powerpc ABI, so a new MACHINE_ARCH was created to deal with this.
Additionaly, the SPE opcodes overlap with Altivec, so these are mutually
exclusive.  Taking advantage of this fact, a new file, powerpc/booke/spe.c, was
created with the same function set as in powerpc/powerpc/altivec.c, so it
becomes effectively a drop-in replacement.  setjmp/longjmp were modified to save
the upper 32-bits of the now-64-bit GPRs (upper 32-bits are only accessible by
the SPE).

Note: This does _not_ support the SPE in the e500v1, as the e500v1 SPE does not
support double-precision floating point.

Also, without a new MACHINE_ARCH it would be impossible to provide binary
packages which utilize the SPE.

Additionally, no work has been done to support ports, work is needed for this.
This also means no newer gcc can yet be used.  However, gcc's powerpc support
has been refactored which would make adding a powerpcspe-freebsd target very
easy.

Test Plan:
This was lightly tested on a RouterBoard RB800 and an AmigaOne A1222
(P1022-based) board, compiled against the new ABI.  Base system utilities
(/bin/sh, /bin/ls, etc) still function appropriately, the system is able to boot
multiuser.

Reviewed By:	bdrewery, imp
Relnotes:	yes
Differential Revision:	https://reviews.freebsd.org/D5683
2016-10-22 01:57:15 +00:00

54 lines
1.9 KiB
C

/* $NetBSD: fpsetround.c,v 1.3 2002/01/13 21:45:48 thorpej Exp $ */
/*
* Copyright (c) 2016 Justin Hibbits
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Dan Winship.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/types.h>
#include <machine/spr.h>
#include <ieeefp.h>
#ifndef _SOFT_FLOAT
fp_rnd_t
fpsetround(fp_rnd_t rnd_dir)
{
uint32_t fpscr;
fp_rnd_t old;
__asm__ __volatile("mfspr %0, %1" : "=r"(fpscr) : "K"(SPR_SPEFSCR) );
old = (fp_rnd_t)(fpscr & 0x3);
fpscr = (fpscr & 0xfffffffc) | rnd_dir;
__asm__ __volatile("mtspr %1, %0" :: "r"(fpscr), "K"(SPR_SPEFSCR));
return (old);
}
#endif