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deps/libcbor/src/cbor/encoding.c  view on Meta::CPAN

size_t cbor_encode_half(float value, unsigned char *buffer,
                        size_t buffer_size) {
  /* Assuming value is normalized */
  uint32_t val = ((union _cbor_float_helper){.as_float = value}).as_uint;
  uint16_t res;
  uint8_t exp = (uint8_t)((val & 0x7F800000u) >>
                          23u); /* 0b0111_1111_1000_0000_0000_0000_0000_0000 */
  uint32_t mant =
      val & 0x7FFFFFu; /* 0b0000_0000_0111_1111_1111_1111_1111_1111 */
  if (exp == 0xFF) {   /* Infinity or NaNs */
    if (value != value) {
      res = (uint16_t)0x007e00; /* Not IEEE semantics - required by CBOR
                                   [s. 3.9] */
    } else {
      res = (uint16_t)((val & 0x80000000u) >> 16u | 0x7C00u |
                       (mant ? 1u : 0u) << 15u);
    }
  } else if (exp == 0x00) { /* Zeroes or subnorms */
    res = (uint16_t)((val & 0x80000000u) >> 16u | mant >> 13u);
  } else { /* Normal numbers */

deps/libcbor/src/cbor/encoding.h  view on Meta::CPAN

size_t cbor_encode_undef(unsigned char *, size_t);

/** Encodes a half-precision float
 *
 * Since there is no native representation or semantics for half floats
 * in the language, we use single-precision floats, as every value that
 * can be expressed as a half-float can also be expressed as a float.
 *
 * This however means that not all floats passed to this function can be
 * unambiguously encoded. The behavior is as follows:
 *  - Infinity, NaN are preserved
 *  - Zero is preserved
 *  - Denormalized numbers keep their sign bit and 10 most significant bit of
 * the significand
 *  - All other numbers
 *   - If the logical value of the exponent is < -24, the output is zero
 *   - If the logical value of the exponent is between -23 and -14, the output
 *     is cut off to represent the 'magnitude' of the input, by which we
 *     mean (-1)^{signbit} x 1.0e{exponent}. The value in the significand is
 * lost.
 *   - In all other cases, the sign bit, the exponent, and 10 most significant

ppport.h  view on Meta::CPAN

    s++; if (s == send || (*s != 'F' && *s != 'f')) return 0;
    s++; if (s < send && (*s == 'I' || *s == 'i')) {
      s++; if (s == send || (*s != 'N' && *s != 'n')) return 0;
      s++; if (s == send || (*s != 'I' && *s != 'i')) return 0;
      s++; if (s == send || (*s != 'T' && *s != 't')) return 0;
      s++; if (s == send || (*s != 'Y' && *s != 'y')) return 0;
      s++;
    }
    sawinf = 1;
  } else if (*s == 'N' || *s == 'n') {
    /* XXX TODO: There are signaling NaNs and quiet NaNs. */
    s++; if (s == send || (*s != 'A' && *s != 'a')) return 0;
    s++; if (s == send || (*s != 'N' && *s != 'n')) return 0;
    s++;
    sawnan = 1;
  } else
    return 0;

  if (sawinf) {
    numtype &= IS_NUMBER_NEG; /* Keep track of sign  */
    numtype |= IS_NUMBER_INFINITY | IS_NUMBER_NOT_INT;