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i386_amd64.h
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Sep 2 2020, 6:52 AM
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i386_amd64.h
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/* IEEE floating point type, constant and function definitions.
* XXX: {FP,SSE}*FLD and {FP,SSE}*OFF are undocumented pollution.
*/
#ifndef _SYS_CDEFS_H_
#error this file needs sys/cdefs.h as a prerequisite
#endif
/*
* Rounding modes.
*/
typedef enum {
FP_RN=0, /* round to nearest */
FP_RM, /* round down towards minus infinity */
FP_RP, /* round up towards plus infinity */
FP_RZ /* truncate */
} fp_rnd_t;
/*
* Precision (i.e., rounding precision) modes.
*/
typedef enum {
FP_PS=0, /* 24 bit (single-precision) */
FP_PRS, /* reserved */
FP_PD, /* 53 bit (double-precision) */
FP_PE /* 64 bit (extended-precision) */
} fp_prec_t;
#define fp_except_t int
/*
* Exception bit masks.
*/
#define FP_X_INV 0x01 /* invalid operation */
#define FP_X_DNML 0x02 /* denormal */
#define FP_X_DZ 0x04 /* zero divide */
#define FP_X_OFL 0x08 /* overflow */
#define FP_X_UFL 0x10 /* underflow */
#define FP_X_IMP 0x20 /* (im)precision */
#define FP_X_STK 0x40 /* stack fault */
/*
* FPU control 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 /* rounding control field */
/*
* FPU status word bit-field masks.
*/
#define FP_STKY_FLD 0x3f /* sticky flags field */
/*
* 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 /* rounding control offset */
/*
* FPU status word bit-field offsets (shift counts).
*/
#define FP_STKY_OFF 0 /* sticky flags offset */
#ifdef __GNUCLIKE_ASM
#define __fldcw(addr) __asm __volatile("fldcw %0" : : "m" (*(addr)))
#define __fldenv(addr) __asm __volatile("fldenv %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)))
#define __ldmxcsr(addr) __asm __volatile("ldmxcsr %0" : : "m" (*(addr)))
#define __stmxcsr(addr) __asm __volatile("stmxcsr %0" : "=m" (*(addr)))
/*
* 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 void
__fnldcw(unsigned short _cw, unsigned short _newcw)
{
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;
}
}
__fldcw(&_newcw);
}
#endif /* __GNUCLIKE_ASM */

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