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40 .Nd IEEE floating point interface
45 FP_RN, /* round to nearest */
46 FP_RM, /* round down to minus infinity */
47 FP_RP, /* round up to plus infinity */
54 .Fn fpsetround "fp_rnd_t direction"
57 FP_PS, /* 24 bit (single-precision) */
58 FP_PRS, /* reserved */
59 FP_PD, /* 53 bit (double-precision) */
60 FP_PE /* 64 bit (extended-precision) */
66 .Fn fpsetprec "fp_prec_t precision"
68 #define fp_except_t int
69 #define FP_X_INV 0x01 /* invalid operation */
70 #define FP_X_DNML 0x02 /* denormal */
71 #define FP_X_DZ 0x04 /* zero divide */
72 #define FP_X_OFL 0x08 /* overflow */
73 #define FP_X_UFL 0x10 /* underflow */
74 #define FP_X_IMP 0x20 /* (im)precision */
75 #define FP_X_STK 0x40 /* stack fault */
80 .Fn fpsetmask "fp_except_t mask"
84 .Fn fpresetsticky "fp_except_t sticky"
86 The routines described herein are deprecated.
87 New code should use the functionality provided by
90 When a floating point exception is detected, the exception sticky flag is
91 set and the exception mask is tested.
92 If the mask is set, then a trap
94 These routines allow both setting the floating point exception
95 masks, and resetting the exception sticky flags after an exception is
97 In addition, they allow setting the floating point rounding mode
103 returns the current floating point rounding mode.
108 sets the floating point rounding mode and returns
114 returns the current floating point precision.
119 sets the floating point precision and returns
120 the previous precision.
125 returns the current floating point exception masks.
130 sets the floating point exception masks and returns the
136 returns the current floating point sticky flags.
141 clears the floating point sticky flags and returns
144 Sample code which prevents a trap on divide-by-zero:
145 .Bd -literal -offset indent
150 fpresetsticky(FP_X_DZ);
153 .Sh IMPLEMENTATION NOTES
158 functions provide functionality unavailable on many platforms.
159 At present, they are implemented only on the i386 and amd64 platforms.
160 Changing precision is not a supported feature:
161 it may be ineffective when code is compiled to take advantage of SSE,
162 and many library functions and compiler optimizations depend upon the
163 default precision for correct behavior.
168 These routines are based on SysV/386 routines of the same name.
170 After a floating point exception and before a mask is set, the sticky
172 If another exception occurs before the sticky
173 flags are reset, then a wrong exception type may be signaled.