newlib/libc/machine/riscv/ieeefp.c

   1 /* Copyright (c) 2017  SiFive Inc. All rights reserved.
   2
   3    This copyrighted material is made available to anyone wishing to use,
   4    modify, copy, or redistribute it subject to the terms and conditions
   5    of the FreeBSD License.   This program is distributed in the hope that
   6    it will be useful, but WITHOUT ANY WARRANTY expressed or implied,
   7    including the implied warranties of MERCHANTABILITY or FITNESS FOR
   8    A PARTICULAR PURPOSE.  A copy of this license is available at
   9    http://www.opensource.org/licenses.
  10 */
  11
  12 #include <ieeefp.h>
  13
  14 #if defined(__riscv_flen) || defined (__riscv_zfinx)
  15 static void
  16 fssr(unsigned value)
  17 {
  18   asm volatile ("fscsr %0" :: "r"(value));
  19 }
  20
  21 static unsigned
  22 frsr()
  23 {
  24   unsigned value;
  25   asm volatile ("frcsr %0" : "=r" (value));
  26   return value;
  27 }
  28
  29 static fp_rnd
  30 frm_fp_rnd (unsigned frm)
  31 {
  32   switch (frm)
  33     {
  34     case 0: return FP_RN;
  35     case 1: return FP_RZ;
  36     case 2: return FP_RM;
  37     case 3: return FP_RP;
  38     /* 4 ~ 7 is invalid value, so just retun FP_RP.  */
  39     default:return FP_RP;
  40     }
  41 }
  42
  43 static fp_except
  44 frm_fp_except (unsigned except)
  45 {
  46   fp_except fp = 0;
  47   if (except & (1 << 0))
  48     fp |= FP_X_IMP;
  49   if (except & (1 << 1))
  50     fp |= FP_X_UFL;
  51   if (except & (1 << 2))
  52     fp |= FP_X_OFL;
  53   if (except & (1 << 3))
  54     fp |= FP_X_DX;
  55   if (except & (1 << 4))
  56     fp |= FP_X_INV;
  57   return fp;
  58 }
  59
  60 static unsigned
  61 frm_except(fp_except fp)
  62 {
  63   unsigned except = 0;
  64   if (fp & FP_X_IMP)
  65     except |= (1 << 0);
  66   if (fp & FP_X_UFL)
  67     except |= (1 << 1);
  68   if (fp & FP_X_OFL)
  69     except |= (1 << 2);
  70   if (fp & FP_X_DX)
  71     except |= (1 << 3);
  72   if (fp & FP_X_INV)
  73     except |= (1 << 4);
  74   return except;
  75 }
  76
  77 #endif /* __riscv_flen */
  78
  79 fp_except
  80 fpgetmask(void)
  81 {
  82   return 0;
  83 }
  84
  85 fp_rnd
  86 fpgetround(void)
  87 {
  88 #if defined(__riscv_flen) || defined (__riscv_zfinx)
  89   unsigned rm = (frsr () >> 5) & 0x7;
  90   return frm_fp_rnd (rm);
  91 #else
  92   return FP_RZ;
  93 #endif /* __riscv_flen */
  94 }
  95
  96 fp_except
  97 fpgetsticky(void)
  98 {
  99 #if defined(__riscv_flen) || defined (__riscv_zfinx)
 100   return frm_fp_except(frsr ());
 101 #else
 102   return 0;
 103 #endif /* __riscv_flen */
 104 }
 105
 106 fp_except
 107 fpsetmask(fp_except mask)
 108 {
 109   return -1;
 110 }
 111
 112 fp_rnd
 113 fpsetround(fp_rnd rnd_dir)
 114 {
 115 #if defined(__riscv_flen) || defined (__riscv_zfinx)
 116   unsigned fsr = frsr ();
 117   unsigned rm = (fsr >> 5) & 0x7;
 118   unsigned new_rm;
 119   switch (rnd_dir)
 120     {
 121     case FP_RN: new_rm = 0; break;
 122     case FP_RZ: new_rm = 1; break;
 123     case FP_RM: new_rm = 2; break;
 124     case FP_RP: new_rm = 3; break;
 125     default:    return -1;
 126     }
 127   fssr (new_rm << 5 | fsr & 0x1f);
 128   return frm_fp_rnd (rm);
 129 #else
 130   return -1;
 131 #endif /* __riscv_flen */
 132 }
 133
 134 fp_except
 135 fpsetsticky(fp_except sticky)
 136 {
 137 #if defined(__riscv_flen) || defined (__riscv_zfinx)
 138   unsigned fsr = frsr ();
 139   fssr (frm_except(sticky) | (fsr & ~0x1f));
 140   return frm_fp_except(fsr);
 141 #else
 142   return -1;
 143 #endif /* __riscv_flen */
 144 }