/* $Id: fpuex.c,v 1.6 2012/07/21 21:11:40 kostik Exp kostik $ */
/* /usr/local/opt/gcc-4.7.1/bin/gcc -Wall -Wextra -msse -O -g -o fpuex32 fpuex.c */

#include <sys/types.h>
#include <err.h>
#include <errno.h>
#include <signal.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ucontext.h>
#if defined(__amd64__)
#include <machine/fpu.h>
#elif defined(__i386__)
#include <machine/npx.h>
#endif

static void
handler(int signo __unused, siginfo_t *info, void *v)
{
	ucontext_t *uap;
	mcontext_t *mc;
#if defined(__amd64__)
	struct savefpu *sf;
#elif defined(__i386__)
	struct savexmm *sf;
#endif
	u_short cw;

	uap = v;
	mc = &uap->uc_mcontext;
	sf = &mc->mc_fpstate;
	printf("intr handler: trapno %d code %d cw 0x%04x sw 0x%04x mxcsr 0x%08x ip 0x%lx\n",
	    info->si_trapno, info->si_code,
#if defined(__amd64__)
	    sf->sv_env.en_cw, sf->sv_env.en_sw, sf->sv_env.en_mxcsr,
	    sf->sv_env.en_rip
#elif defined(__i386__)
	    sf->sv_env.en_cw, sf->sv_env.en_sw,
	    sf->sv_env.en_mxcsr, (unsigned long)sf->sv_env.en_fip
#endif
	    );
	__asm __volatile("fnstcw %0" : "=m" (cw));
	printf("handler cw %x\n", cw);
	exit(0);
}

double a[3];

/*
 * a[3] = a[0] / a[1];
 */
static void
x_sse(void)
{

	__asm("movsd\t%1,%%xmm0\n\t"
	      "divsd\t%2,%%xmm0\n\t"
	      "movsd\t%%xmm0,%0\n"
	    : "=m" (a[3]) : "m" (a[0]), "m" (a[1]) : "xmm0");
}

static void
x_x87(void)
{

	__asm("fldl\t%1\n\t"
	      "fdivl\t%2\n\t"
	      "fstl\t%0\n" : "=m" (a[3]) : "m" (a[0]), "m" (a[1]));
}

static void
usage(void)
{
	
	fprintf(stderr, "fpuex sse|x87\n");
	exit(1);
}

int
main(int argc, char *argv[])
{
	struct sigaction sa;
	uint32_t mxcsr;
	uint16_t cw;
	int use_sse;

	if (argc == 1) {
#if defined(__amd64__)
		use_sse = 1;
#elif defined(__i386__)
		use_sse = 0;
#endif
	} else if (argc != 2)
		usage();
	else {
		if (!strcmp(argv[1], "sse"))
			use_sse = 1;
		else if (!strcmp(argv[1], "x87"))
			use_sse = 0;
		else
			usage();
	}

	bzero(&sa, sizeof(sa));
	sa.sa_sigaction = handler;
	sa.sa_flags = SA_SIGINFO;
	if (sigaction(SIGFPE, &sa, NULL) == -1)
		err(1, "sigaction SIGFPE");

	mxcsr = 0;
	__asm __volatile("ldmxcsr %0" : : "m" (mxcsr));
	cw = 0;
	__asm __volatile("fldcw %0" : : "m" (cw));
	a[0] = 1.0;
	a[1] = 0.0;
	if (use_sse)
		x_sse();
	else
		x_x87();
	return (0);
}