fbit_gen.c

picoos源码。The RTOS and the TCP/IP stack will be built automatically.

  }
#endif
  if ((bf & 0x000F) == 0)
  {
    bit |= 4;
    bf >>= 4;
  }
  if ((bf & 0x0003) == 0)
  {
    bit |= 2;
    bf >>= 2;
  }
  if ((bf & 0x0001) == 0)
  {
    bit |= 1;
  }

#if (POSCFG_ROUNDROBIN == 0)
  return bit;
#else /* POSCFG_ROUNDROBIN */
  return (bit + rrOffset) & (MVAR_BITS - 1);
#endif /* POSCFG_ROUNDROBIN */
}

#else /* POSCFG_FBIT_BITSHIFT */

/*
 * Fast generic findbit() -function for 8/16/32 bit architectures.
 * The code supports roundrobin and standard-scheduling.
 *
 * Speed:
 *   8 bit: 3 if-branches
 *  16 bit: 4 if-branches
 *  32 bit: 5 if-branches
 *
 * When roundrobin is enabled, also two shift-, one and-, one or-
 * and one addition operation are needed.
 *
 * Note:
 *  This function can be used for architectures that
 *  are slow in bit shifting. This function may
 *  be used for 8 or 16 bit architectures.
 */

#if (POSCFG_ROUNDROBIN == 0)

UVAR_t p_pos_findbit(const UVAR_t bitfield)
{
  UVAR_t bf = bitfield;
  UVAR_t bit;

#else /* POSCFG_ROUNDROBIN */

UVAR_t p_pos_findbit(const UVAR_t bitfield, UVAR_t rrOffset)
{
  UVAR_t bf;
  UVAR_t bit;
  
  bf = (bitfield << (MVAR_BITS - rrOffset)) | (bitfield >> rrOffset);

#endif /* POSCFG_ROUNDROBIN */

#if (MVAR_BITS == 32)
  if (bf & 0x0000FFFF) {
#endif
#if (MVAR_BITS >= 16)
    if (bf & 0x00FF) {
#endif
      if (bf & 0x0F) {
        if (bf & 0x03) {
          if (bf & 0x01) {
            bit = 0;
          } else {
            bit = 1;
          }
        } else {
          if (bf & 0x04) {
            bit = 2;
          } else {
            bit = 3;
          }
        }
      } else {
        if (bf & 0x30) {
          if (bf & 0x10) {
            bit = 4;
          } else {
            bit = 5;
          }
        } else {
          if (bf & 0x40) {
            bit = 6;
          } else {
            bit = 7;
          }
        }
      }
#if (MVAR_BITS >= 16)
    } else {
      if (bf & 0x0F00) {
        if (bf & 0x0300) {
          if (bf & 0x0100) {
            bit = 8;
          } else {
            bit = 9;
          }
        } else {
          if (bf & 0x0400) {
            bit = 10;
          } else {
            bit = 11;
          }
        }
      } else {
        if (bf & 0x3000) {
          if (bf & 0x1000) {
            bit = 12;
          } else {
            bit = 13;
          }
        } else {
          if (bf & 0x4000) {
            bit = 14;
          } else {
            bit = 15;
          }
        }
      }
    }  
#endif
#if (MVAR_BITS == 32)
  } else { 
    if (bf & 0x00FF0000) {
      if (bf & 0x000F0000) {
        if (bf & 0x00030000) {
          if (bf & 0x00010000) {
            bit = 16;
          } else {
            bit = 17;
          }
        } else {
          if (bf & 0x00040000) {
            bit = 18;
          } else {
            bit = 19;
          }
        }
      } else {
        if (bf & 0x00300000) {
          if (bf & 0x00100000) {
            bit = 20;
          } else {
            bit = 21;
          }
        } else {
          if (bf & 0x00400000) {
            bit = 22;
          } else {
            bit = 23;
          }
        }
      }
    } else {
      if (bf & 0x0F000000) {
        if (bf & 0x03000000) {
          if (bf & 0x01000000) {
            bit = 24;
          } else {
            bit = 25;
          }
        } else {
          if (bf & 0x04000000) {
            bit = 26;
          } else {
            bit = 27;
          }
        }
      } else {
        if (bf & 0x30000000) {
          if (bf & 0x10000000) {
            bit = 28;
          } else {
            bit = 29;
          }
        } else {
          if (bf & 0x40000000) {
            bit = 30;
          } else {
            bit = 31;
          }
        }
      }
    }  
  }
#endif

#if (POSCFG_ROUNDROBIN == 0)
  return bit;
#else /* POSCFG_ROUNDROBIN */
  return (bit + rrOffset) & (MVAR_BITS - 1);
#endif /* POSCFG_ROUNDROBIN */
}

#endif /* POSCFG_FBIT_BITSHIFT */
#else  /* FASTCODE */
#if (POSCFG_ROUNDROBIN == 0)

/*
 * Slow but small generic findbit() -function for all architectures.
 * The code supports standard-scheduling.
 *
 */

UVAR_t p_pos_findbit(const UVAR_t bitfield)
{
  UVAR_t bf = bitfield;
  UVAR_t bit;
  
  for (bit = 0; bit < MVAR_BITS; bit++)
  {
    if (bf & 1)
      break;
    bf >>= 1;
  }
 
  return bit;
}

#else /* POSCFG_ROUNDROBIN */

/*
 * Slow but small generic findbit() -function for all architectures.
 * The code supports roundrobin-scheduling.
 *
 */

UVAR_t p_pos_findbit(const UVAR_t bitfield, UVAR_t rrOffset)
{
  UVAR_t bf;
  UVAR_t bit;
  
  bf = (bitfield << (MVAR_BITS - rrOffset)) | (bitfield >> rrOffset);
  
  for (bit = 0; bit < MVAR_BITS; bit++)
  {
    if (bf & 1)
      break;
    bf >>= 1;
  }
 
  return (bit + rrOffset) & (MVAR_BITS - 1);
}

#endif  /* ROUNDROBIN */
#endif  /* FASTCODE */
#endif  /* POSCFG_FBIT_USE_LUTABLE */