175 lines
4.0 KiB
C++
175 lines
4.0 KiB
C++
/*
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Copyright (C) 2012 Paul Davis
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include "libpbd-config.h"
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#define _XOPEN_SOURCE 600
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#include <cstring> // for memset
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#include <cstdlib>
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#include <stdint.h>
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#include <assert.h>
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#ifdef PLATFORM_WINDOWS
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#include <intrin.h>
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#endif
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#include "pbd/fpu.h"
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#include "pbd/error.h"
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#include "i18n.h"
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using namespace PBD;
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using namespace std;
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FPU::FPU ()
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{
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unsigned long cpuflags = 0;
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_flags = Flags (0);
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#if !( (defined __x86_64__) || (defined __i386__) ) // !ARCH_X86
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return;
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#else
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#ifdef PLATFORM_WINDOWS
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#ifndef USE_X86_64_ASM
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/* no 32 bit version of assembler for windows */
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return;
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#else
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// Get CPU flags using Microsoft function
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// It works for both 64 and 32 bit systems
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// no need to use assembler for getting info from register, this function does this for us
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int cpuInfo[4];
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__cpuid (cpuInfo, 1);
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cpuflags = cpuInfo[3];
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#endif
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#else
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#ifndef _LP64 /* *nix; 32 bit version. This odd macro constant is required because we need something that identifies this as a 32 bit
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build on Linux and on OS X. Anything that serves this purpose will do, but this is the best thing we've identified
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so far.
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*/
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asm volatile (
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"mov $1, %%eax\n"
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"pushl %%ebx\n"
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"cpuid\n"
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"movl %%edx, %0\n"
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"popl %%ebx\n"
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: "=r" (cpuflags)
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:
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: "%eax", "%ecx", "%edx"
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);
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#else /* *nix; 64 bit version */
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/* asm notes: although we explicitly save&restore rbx, we must tell
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gcc that ebx,rbx is clobbered so that it doesn't try to use it as an intermediate
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register when storing rbx. gcc 4.3 didn't make this "mistake", but gcc 4.4
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does, at least on x86_64.
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*/
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asm volatile (
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"pushq %%rbx\n"
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"movq $1, %%rax\n"
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"cpuid\n"
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"movq %%rdx, %0\n"
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"popq %%rbx\n"
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: "=r" (cpuflags)
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:
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: "%rax", "%rbx", "%rcx", "%rdx"
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);
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#endif /* USE_X86_64_ASM */
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#endif /* PLATFORM_WINDOWS */
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if (cpuflags & (1<<25)) {
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_flags = Flags (_flags | (HasSSE|HasFlushToZero));
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}
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if (cpuflags & (1<<26)) {
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_flags = Flags (_flags | HasSSE2);
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}
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if (cpuflags & (1 << 24)) {
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char** fxbuf = 0;
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/* DAZ wasn't available in the first version of SSE. Since
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setting a reserved bit in MXCSR causes a general protection
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fault, we need to be able to check the availability of this
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feature without causing problems. To do this, one needs to
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set up a 512-byte area of memory to save the SSE state to,
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using fxsave, and then one needs to inspect bytes 28 through
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31 for the MXCSR_MASK value. If bit 6 is set, DAZ is
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supported, otherwise, it isn't.
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*/
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#ifndef HAVE_POSIX_MEMALIGN
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fxbuf = (char **) malloc (sizeof (char *));
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assert (fxbuf);
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*fxbuf = (char *) malloc (512);
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assert (*fxbuf);
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#else
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(void) posix_memalign ((void **) &fxbuf, 16, sizeof (char *));
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assert (fxbuf);
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(void) posix_memalign ((void **) fxbuf, 16, 512);
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assert (*fxbuf);
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#endif
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memset (*fxbuf, 0, 512);
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#ifdef COMPILER_MSVC
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__asm {
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mov eax, fxbuf
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fxsave [eax]
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};
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#else
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asm volatile (
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"fxsave (%0)"
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:
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: "r" (*fxbuf)
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: "memory"
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);
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#endif
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uint32_t mxcsr_mask = *((uint32_t*) &((*fxbuf)[28]));
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/* if the mask is zero, set its default value (from intel specs) */
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if (mxcsr_mask == 0) {
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mxcsr_mask = 0xffbf;
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}
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if (mxcsr_mask & (1<<6)) {
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_flags = Flags (_flags | HasDenormalsAreZero);
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}
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free (*fxbuf);
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free (fxbuf);
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}
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#endif
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}
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FPU::~FPU ()
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{
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}
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