sp_div.c 3.4 KB

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  1. // SPDX-License-Identifier: GPL-2.0-only
  2. /* IEEE754 floating point arithmetic
  3. * single precision
  4. */
  5. /*
  6. * MIPS floating point support
  7. * Copyright (C) 1994-2000 Algorithmics Ltd.
  8. */
  9. #include "ieee754sp.h"
  10. union ieee754sp ieee754sp_div(union ieee754sp x, union ieee754sp y)
  11. {
  12. unsigned int rm;
  13. int re;
  14. unsigned int bm;
  15. COMPXSP;
  16. COMPYSP;
  17. EXPLODEXSP;
  18. EXPLODEYSP;
  19. ieee754_clearcx();
  20. FLUSHXSP;
  21. FLUSHYSP;
  22. switch (CLPAIR(xc, yc)) {
  23. case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
  24. case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
  25. case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
  26. case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
  27. case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
  28. return ieee754sp_nanxcpt(y);
  29. case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
  30. case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
  31. case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
  32. case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
  33. case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
  34. case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
  35. return ieee754sp_nanxcpt(x);
  36. case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
  37. case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
  38. case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
  39. case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
  40. return y;
  41. case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
  42. case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
  43. case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
  44. case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
  45. case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):
  46. return x;
  47. /*
  48. * Infinity handling
  49. */
  50. case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
  51. ieee754_setcx(IEEE754_INVALID_OPERATION);
  52. return ieee754sp_indef();
  53. case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
  54. case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
  55. case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
  56. return ieee754sp_zero(xs ^ ys);
  57. case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
  58. case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
  59. case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
  60. return ieee754sp_inf(xs ^ ys);
  61. /*
  62. * Zero handling
  63. */
  64. case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
  65. ieee754_setcx(IEEE754_INVALID_OPERATION);
  66. return ieee754sp_indef();
  67. case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
  68. case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
  69. ieee754_setcx(IEEE754_ZERO_DIVIDE);
  70. return ieee754sp_inf(xs ^ ys);
  71. case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
  72. case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
  73. return ieee754sp_zero(xs == ys ? 0 : 1);
  74. case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
  75. SPDNORMX;
  76. fallthrough;
  77. case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
  78. SPDNORMY;
  79. break;
  80. case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
  81. SPDNORMX;
  82. break;
  83. case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM):
  84. break;
  85. }
  86. assert(xm & SP_HIDDEN_BIT);
  87. assert(ym & SP_HIDDEN_BIT);
  88. /* provide rounding space */
  89. xm <<= 3;
  90. ym <<= 3;
  91. /* now the dirty work */
  92. rm = 0;
  93. re = xe - ye;
  94. for (bm = SP_MBIT(SP_FBITS + 2); bm; bm >>= 1) {
  95. if (xm >= ym) {
  96. xm -= ym;
  97. rm |= bm;
  98. if (xm == 0)
  99. break;
  100. }
  101. xm <<= 1;
  102. }
  103. rm <<= 1;
  104. if (xm)
  105. rm |= 1; /* have remainder, set sticky */
  106. assert(rm);
  107. /* normalise rm to rounding precision ?
  108. */
  109. while ((rm >> (SP_FBITS + 3)) == 0) {
  110. rm <<= 1;
  111. re--;
  112. }
  113. return ieee754sp_format(xs == ys ? 0 : 1, re, rm);
  114. }