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nanosec: updated.

--- a/nanosec.c

+++ b/nanosec.c

@@ -2,41 +2,8 @@

 #include <libc.h>

 #include <tos.h>

-/*

- * This code is a mixture of cpuid(1) and the nanosec() found in vmx,

- * in order to force the use of nsec(2) in case we are running in a

- * virtualized environment where the clock is mis-bhyve-ing.

- */

+#define Nsec 1000000000ULL

-typedef struct Res {

-	ulong ax, bx, cx, dx;

-} Res;

-

-static uchar _cpuid[] = {

-	0x5E,			/* POP SI (PC) */

-	0x5D,			/* POP BP (Res&) */

-	0x58,			/* POP AX */

-	0x59,			/* POP CX */

-

-	0x51,			/* PUSH CX */

-	0x50,			/* PUSH AX */

-	0x55,			/* PUSH BP */

-	0x56,			/* PUSH SI */

-

-	0x31, 0xDB,		/* XOR BX, BX */

-	0x31, 0xD2,		/* XOR DX, DX */

-

-	0x0F, 0xA2,		/* CPUID */

-

-	0x89, 0x45, 0x00,	/* MOV AX, 0(BP) */

-	0x89, 0x5d, 0x04,	/* MOV BX, 4(BP) */

-	0x89, 0x4d, 0x08,	/* MOV CX, 8(BP) */

-	0x89, 0x55, 0x0C,	/* MOV DX, 12(BP) */

-	0xC3,			/* RET */

-};

-

-static Res (*cpuid)(ulong ax, ulong cx) = (Res(*)(ulong, ulong)) _cpuid;

-

 /*

  * nsec() is wallclock and can be adjusted by timesync

  * so need to use cycles() instead, but fall back to

@@ -46,54 +13,16 @@

 nanosec(void)

 {

 	static uvlong fasthz, xstart;

-	char buf[13], path[128];

-	ulong w;

-	uvlong x, div;

-	int fd;

-	Res r;

+	uvlong x;

 	if(fasthz == ~0ULL)

 		return nsec() - xstart;

 	if(fasthz == 0){

-		/* first long in a.out header */

-		snprint(path, sizeof path, "/proc/%d/text", getpid());

-		fd = open(path, OREAD);

-		if(fd < 0)

-			goto Wallclock;

-		if(read(fd, buf, 4) != 4){

-			close(fd);

-			goto Wallclock;

-		}

-		close(fd);

-

-		w = ((ulong *) buf)[0];

-

-		switch(w){

-		default:

-			goto Wallclock;

-		case 0x978a0000:	/* amd64 */

-			/* patch out POP BP -> POP AX */

-			_cpuid[1] = 0x58;

-		case 0xeb010000:	/* 386 */

-			break;

-		}

-		segflush(_cpuid, sizeof(_cpuid));

-

-		r = cpuid(0x40000000, 0);

-		((ulong *) buf)[0] = r.bx;

-		((ulong *) buf)[1] = r.cx;

-		((ulong *) buf)[2] = r.dx;

-		buf[12] = 0;

-

-		if(strstr(buf, "bhyve") != nil)

-			goto Wallclock;

-

 		if(_tos->cyclefreq){

 			fasthz = _tos->cyclefreq;

 			cycles(&xstart);

 		} else {

-Wallclock:

 			fasthz = ~0ULL;

 			xstart = nsec();

 		}

@@ -102,8 +31,8 @@

 	cycles(&x);

 	x -= xstart;

-	/* this is ugly */

-	for(div = 1000000000ULL; x < 0x1999999999999999ULL && div > 1 ; div /= 10ULL, x *= 10ULL);

+	uvlong q = x / fasthz;

+	uvlong r = x % fasthz;

-	return x / (fasthz / div);

+	return q*Nsec + r*Nsec/fasthz;

 }