/*-
+ * Copyright (c) 2003 Peter Wemm.
* Copyright (c) 1990 Andrew Moore, Talke Studio
* All rights reserved.
*
* SUCH DAMAGE.
*
* from: @(#) ieeefp.h 1.0 (Berkeley) 9/23/93
- * $FreeBSD: src/sys/i386/include/ieeefp.h,v 1.8 2003/01/19 06:01:33 marcel Exp $
- */
-
-/*
- * IEEE floating point type and constant definitions.
+ * $FreeBSD: src/sys/i386/include/ieeefp.h,v 1.14 2008/01/11 18:59:35 bde Exp $
*/
#ifndef _CPU_IEEEFP_H_
#define _CPU_IEEEFP_H_
/*
- * FP rounding modes
+ * IEEE floating point type, constant and function definitions.
+ * XXX: FP*FLD and FP*OFF are undocumented pollution.
+ */
+
+/*
+ * Rounding modes.
*/
typedef enum {
FP_RN=0, /* round to nearest */
- FP_RM, /* round down to minus infinity */
- FP_RP, /* round up to plus infinity */
+ FP_RM, /* round down towards minus infinity */
+ FP_RP, /* round up towards plus infinity */
FP_RZ /* truncate */
} fp_rnd_t;
/*
- * FP precision modes
+ * Precision (i.e., rounding precision) modes.
*/
typedef enum {
FP_PS=0, /* 24 bit (single-precision) */
#define fp_except_t int
/*
- * FP exception masks
+ * Exception bit masks.
*/
#define FP_X_INV 0x01 /* invalid operation */
#define FP_X_DNML 0x02 /* denormal */
#define FP_X_STK 0x40 /* stack fault */
/*
- * FP registers
+ * FPU control word bit-field masks.
*/
-#define FP_MSKS_REG 0 /* exception masks */
-#define FP_PRC_REG 0 /* precision */
-#define FP_RND_REG 0 /* direction */
-#define FP_STKY_REG 1 /* sticky flags */
+#define FP_MSKS_FLD 0x3f /* exception masks field */
+#define FP_PRC_FLD 0x300 /* precision control field */
+#define FP_RND_FLD 0xc00 /* rounding control field */
/*
- * FP register bit field masks
+ * FPU status word bit-field masks.
*/
-#define FP_MSKS_FLD 0x3f /* exception masks field */
-#define FP_PRC_FLD 0x300 /* precision control field */
-#define FP_RND_FLD 0xc00 /* round control field */
#define FP_STKY_FLD 0x3f /* sticky flags field */
/*
- * FP register bit field offsets
+ * FPU control word bit-field offsets (shift counts).
*/
#define FP_MSKS_OFF 0 /* exception masks offset */
#define FP_PRC_OFF 8 /* precision control offset */
-#define FP_RND_OFF 10 /* round control offset */
+#define FP_RND_OFF 10 /* rounding control offset */
+
+/*
+ * FPU status word bit-field offsets (shift counts).
+ */
#define FP_STKY_OFF 0 /* sticky flags offset */
#ifdef __GNUC__
+#define __fldcw(addr) __asm __volatile("fldcw %0" : : "m" (*(addr)))
#define __fldenv(addr) __asm __volatile("fldenv %0" : : "m" (*(addr)))
-#define __fnstenv(addr) __asm __volatile("fnstenv %0" : "=m" (*(addr)))
+#define __fnclex() __asm __volatile("fnclex")
#define __fnstcw(addr) __asm __volatile("fnstcw %0" : "=m" (*(addr)))
+#define __fnstenv(addr) __asm __volatile("fnstenv %0" : "=m" (*(addr)))
#define __fnstsw(addr) __asm __volatile("fnstsw %0" : "=m" (*(addr)))
/*
- * return the contents of a FP register
+ * Load the control word. Be careful not to trap if there is a currently
+ * unmasked exception (ones that will become freshly unmasked are not a
+ * problem). This case must be handled by a save/restore of the
+ * environment or even of the full x87 state. Accessing the environment
+ * is very inefficient, so only do it when necessary.
*/
-static __inline__ int
-__fpgetreg(int _reg)
+static __inline void
+__fnldcw(unsigned short _cw, unsigned short _newcw)
{
- unsigned short _mem;
-
- /*-
- * This is more efficient than it looks. The switch gets optimized
- * away if _reg is constant.
- *
- * The default case only supports _reg == 0. We could handle more
- * registers (e.g., tags) using fnstenv, but the interface doesn't
- * support more.
- */
- switch(_reg) {
- default:
- __fnstcw(&_mem);
- break;
- case FP_STKY_REG:
- __fnstsw(&_mem);
- break;
+ struct {
+ unsigned _cw;
+ unsigned _other[6];
+ } _env;
+ unsigned short _sw;
+
+ if ((_cw & FP_MSKS_FLD) != FP_MSKS_FLD) {
+ __fnstsw(&_sw);
+ if (((_sw & ~_cw) & FP_STKY_FLD) != 0) {
+ __fnstenv(&_env);
+ _env._cw = _newcw;
+ __fldenv(&_env);
+ return;
+ }
}
- return _mem;
+ __fldcw(&_newcw);
}
-/*
- * set a FP mode; return previous mode
- */
-static __inline__ int
-__fpsetreg(int _m, int _reg, int _fld, int _off)
+static __inline fp_rnd_t
+fpgetround(void)
{
- unsigned _env[7];
- unsigned _p;
-
- /*
- * _reg == 0 could be handled better using fnstcw/fldcw.
- */
- __fnstenv(_env);
- _p = (_env[_reg] & _fld) >> _off;
- _env[_reg] = (_env[_reg] & ~_fld) | (_m << _off & _fld);
- __fldenv(_env);
- return _p;
+ unsigned short _cw;
+
+ __fnstcw(&_cw);
+ return ((fp_rnd_t)((_cw & FP_RND_FLD) >> FP_RND_OFF));
}
-#endif /* __GNUC__ */
+static __inline fp_rnd_t
+fpsetround(fp_rnd_t _m)
+{
+ fp_rnd_t _p;
+ unsigned short _cw, _newcw;
+
+ __fnstcw(&_cw);
+ _p = (fp_rnd_t)((_cw & FP_RND_FLD) >> FP_RND_OFF);
+ _newcw = _cw & ~FP_RND_FLD;
+ _newcw |= (_m << FP_RND_OFF) & FP_RND_FLD;
+ __fnldcw(_cw, _newcw);
+ return (_p);
+}
+
+static __inline fp_prec_t
+fpgetprec(void)
+{
+ unsigned short _cw;
+
+ __fnstcw(&_cw);
+ return ((fp_prec_t)((_cw & FP_PRC_FLD) >> FP_PRC_OFF));
+}
+
+static __inline fp_prec_t
+fpsetprec(fp_prec_t _m)
+{
+ fp_prec_t _p;
+ unsigned short _cw, _newcw;
+
+ __fnstcw(&_cw);
+ _p = (fp_prec_t)((_cw & FP_PRC_FLD) >> FP_PRC_OFF);
+ _newcw = _cw & ~FP_PRC_FLD;
+ _newcw |= (_m << FP_PRC_OFF) & FP_PRC_FLD;
+ __fnldcw(_cw, _newcw);
+ return (_p);
+}
/*
- * SysV/386 FP control interface
+ * Get or set the exception mask.
+ * Note that the x87 mask bits are inverted by the API -- a mask bit of 1
+ * means disable for x87 and SSE, but for fp*mask() it means enable.
*/
-#define fpgetround() ((fp_rnd_t) \
- ((__fpgetreg(FP_RND_REG) & FP_RND_FLD) >> FP_RND_OFF))
-#define fpsetround(m) ((fp_rnd_t) \
- __fpsetreg((m), FP_RND_REG, FP_RND_FLD, FP_RND_OFF))
-#define fpgetprec() ((fp_prec_t) \
- ((__fpgetreg(FP_PRC_REG) & FP_PRC_FLD) >> FP_PRC_OFF))
-#define fpsetprec(m) ((fp_prec_t) \
- __fpsetreg((m), FP_PRC_REG, FP_PRC_FLD, FP_PRC_OFF))
-#define fpgetmask() ((fp_except_t) \
- ((~__fpgetreg(FP_MSKS_REG) & FP_MSKS_FLD) >> FP_MSKS_OFF))
-#define fpsetmask(m) ((fp_except_t) \
- (~__fpsetreg(~(m), FP_MSKS_REG, FP_MSKS_FLD, FP_MSKS_OFF)) & \
- (FP_MSKS_FLD >> FP_MSKS_OFF))
-#define fpgetsticky() ((fp_except_t) \
- ((__fpgetreg(FP_STKY_REG) & FP_STKY_FLD) >> FP_STKY_OFF))
-#define fpresetsticky(m) ((fp_except_t) \
- __fpsetreg(0, FP_STKY_REG, (m), FP_STKY_OFF))
-#define fpsetsticky(m) fpresetsticky(m)
+
+static __inline fp_except_t
+fpgetmask(void)
+{
+ unsigned short _cw;
+
+ __fnstcw(&_cw);
+ return ((~_cw & FP_MSKS_FLD) >> FP_MSKS_OFF);
+}
+
+static __inline fp_except_t
+fpsetmask(fp_except_t _m)
+{
+ fp_except_t _p;
+ unsigned short _cw, _newcw;
+
+ __fnstcw(&_cw);
+ _p = (~_cw & FP_MSKS_FLD) >> FP_MSKS_OFF;
+ _newcw = _cw & ~FP_MSKS_FLD;
+ _newcw |= (~_m << FP_MSKS_OFF) & FP_MSKS_FLD;
+ __fnldcw(_cw, _newcw);
+ return (_p);
+}
+
+static __inline fp_except_t
+fpgetsticky(void)
+{
+ unsigned _ex;
+ unsigned short _sw;
+
+ __fnstsw(&_sw);
+ _ex = (_sw & FP_STKY_FLD) >> FP_STKY_OFF;
+ return ((fp_except_t)_ex);
+}
+
+static __inline fp_except_t
+fpresetsticky(fp_except_t _m)
+{
+ struct {
+ unsigned _cw;
+ unsigned _sw;
+ unsigned _other[5];
+ } _env;
+ fp_except_t _p;
+
+ _m &= FP_STKY_FLD >> FP_STKY_OFF;
+ _p = fpgetsticky();
+ if ((_p & ~_m) == _p)
+ return (_p);
+ if ((_p & ~_m) == 0) {
+ __fnclex();
+ return (_p);
+ }
+ __fnstenv(&_env);
+ _env._sw &= ~_m;
+ __fldenv(&_env);
+ return (_p);
+}
+
+#endif /* __GNUC__ */
/* Suppress prototypes in the MI header. */
#define _IEEEFP_INLINED_ 1
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