runtime/basis/Real/IEEEReal.c

   1 #include "platform.h"
   2
   3 #if !HAS_FEROUND
   4
   5 #if (defined __i386__) || (defined __x86_64__)
   6
   7 /* Macros for accessing the hardware control word. */
   8 #define _FPU_GETCW(cw)   __asm__ ("fnstcw %0" : "=m" (*&cw))
   9 #define _FPU_SETCW(cw)   __asm__ ("fldcw %0" : : "m" (*&cw))
  10 #define _SSE_GETCSR(csr) __asm__ ("stmxcsr %0" : "=m" (*&csr))
  11 #define _SSE_SETCSR(csr) __asm__ ("ldmxcsr %0" : : "m" (*&csr))
  12
  13 #define FPU_ROUNDING_CONTROL_MASK 0x0C00
  14 #define FPU_ROUNDING_CONTROL_SHIFT 10
  15 #define SSE_ROUNDING_CONTROL_MASK 0x00006000
  16 #define SSE_ROUNDING_CONTROL_SHIFT 13
  17
  18 static inline C_Int_t fegetround (void) {
  19         uint16_t fpuControl;
  20
  21         _FPU_GETCW (fpuControl);
  22         return (fpuControl & FPU_ROUNDING_CONTROL_MASK)
  23                >> FPU_ROUNDING_CONTROL_SHIFT;
  24 }
  25
  26 static inline C_Int_t fesetround (C_Int_t mode) {
  27         uint16_t fpuControl;
  28 #ifdef __x86_64__
  29         uint32_t sseControl;
  30 #endif
  31
  32         _FPU_GETCW (fpuControl);
  33         fpuControl &= ~FPU_ROUNDING_CONTROL_MASK;
  34         fpuControl |= mode << FPU_ROUNDING_CONTROL_SHIFT;
  35         _FPU_SETCW (fpuControl);
  36
  37 #ifdef __x86_64__
  38         _SSE_GETCSR (sseControl);
  39         sseControl &= ~SSE_ROUNDING_CONTROL_MASK;
  40         sseControl |= mode << SSE_ROUNDING_CONTROL_SHIFT;
  41         _SSE_SETCSR (sseControl);
  42 #endif
  43         return 0;
  44 }
  45
  46 #elif (defined __UCLIBC__)
  47
  48 /* Use whatever we got from fpu_control.h for this CPU model */
  49 #define FE_MASK (FE_DOWNWARD|FE_TONEAREST|FE_TOWARDZERO|FE_UPWARD)
  50
  51 static inline int fegetround () {
  52         fpu_control_t controlWord;
  53         _FPU_GETCW(controlWord);
  54         return controlWord & FE_MASK;
  55 }
  56
  57 static inline int fesetround (int mode) {
  58         fpu_control_t controlWord;
  59
  60         _FPU_GETCW (controlWord);
  61         controlWord = (controlWord & ~FE_MASK) | mode;
  62         _FPU_SETCW (controlWord);
  63         return 0;
  64 }
  65
  66
  67 #else
  68
  69 #error fe{get,set}round not implemented
  70
  71 #endif
  72
  73 #endif /* !HAS_FEROUND */
  74
  75 C_Int_t IEEEReal_getRoundingMode (void) {
  76   return fegetround ();
  77 }
  78
  79 C_Int_t IEEEReal_setRoundingMode (C_Int_t m) {
  80   assert (m != IEEEReal_RoundingMode_FE_NOSUPPORT);
  81   return fesetround (m);
  82 }