static uint32_t I2Cx_SlaveHandler()

in lib/cmsis/CMSIS/Pack/Example/CMSIS_Driver/I2C_LPC18xx.c [720:834]

• 86 lines of code
• 26 McCabe index (conditional complexity)

static uint32_t I2Cx_SlaveHandler (I2C_RESOURCES *i2c) {
  uint32_t conset = 0;
  uint32_t event  = 0;

  switch (i2c->reg->STAT & 0xF8) {
    case I2C_STAT_SL_ALOST_GC:
      /* Arbitration lost in General call */
      i2c->ctrl->status.arbitration_lost = 1;
    case I2C_STAT_SL_GCA_A:
      /* General address recvd, ACK returned */
      i2c->ctrl->status.general_call     = 1;
      goto slaw_a;

    case I2C_STAT_SL_ALOST_MW:
      /* Arbitration lost SLA+W */
      i2c->ctrl->status.arbitration_lost = 1;
    case I2C_STAT_SL_SLAW_A:
      /* SLA+W received, ACK returned */
slaw_a:
      /* Stalled Slave receiver also resumes here */
      if (!i2c->ctrl->snum || !(i2c->ctrl->flags & I2C_FLAG_SLAVE_RX)) {
        /* Receive buffer unavailable */
        if (i2c->ctrl->stalled) {
          /* Already stalled, abort transaction to prevent dead-loops */
          event = ARM_I2C_EVENT_TRANSFER_DONE |
                  ARM_I2C_EVENT_TRANSFER_INCOMPLETE;
          conset = I2C_CON_STO | i2c->ctrl->con_aa;
          break;
        }
        /* Stall I2C transaction */
        NVIC_DisableIRQ (i2c->i2c_ev_irq);
        i2c->ctrl->stalled = I2C_SLAVE_RX;
        return (ARM_I2C_EVENT_SLAVE_RECEIVE);
      }
      i2c->ctrl->status.direction = 1;
      i2c->ctrl->status.busy      = 1;
      i2c->ctrl->cnt     = 0;
      i2c->ctrl->stalled = 0;
      conset = I2C_CON_AA;
      break;

    case I2C_STAT_SL_DRGC_A:
      /* Data recvd General call, ACK returned */
    case I2C_STAT_SL_DR_A:
      /* Data received, ACK returned */
      i2c->ctrl->sdata[i2c->ctrl->cnt++] = i2c->reg->DAT;
      i2c->ctrl->snum--;
      if (i2c->ctrl->snum) {
        conset = I2C_CON_AA;
      }
      break;

    case I2C_STAT_SL_ALOST_MR:
      /* Arbitration lost SLA+R */
      i2c->ctrl->status.arbitration_lost = 1;
    case I2C_STAT_SL_SLAR_A:
      /* SLA+R received, ACK returned */
      /* Stalled Slave transmitter also resumes here */
      if (!i2c->ctrl->snum || (i2c->ctrl->flags & I2C_FLAG_SLAVE_RX)) {
        /* Transmit buffer unavailable */
        if (i2c->ctrl->stalled) {
          /* Already stalled, abort transaction to prevent dead-loops */
          event = ARM_I2C_EVENT_TRANSFER_DONE |
                  ARM_I2C_EVENT_TRANSFER_INCOMPLETE;
          conset = I2C_CON_STO | i2c->ctrl->con_aa;
          break;
        }
        NVIC_DisableIRQ (i2c->i2c_ev_irq);
        i2c->ctrl->stalled = I2C_SLAVE_TX;
        return (ARM_I2C_EVENT_SLAVE_TRANSMIT);
      }
      i2c->ctrl->status.direction = 0;
      i2c->ctrl->status.busy      = 1;
      i2c->ctrl->cnt     = 0;
      i2c->ctrl->stalled = 0;
    case I2C_STAT_SL_DT_A:
      /* Data transmitted, ACK received */
      i2c->reg->DAT = i2c->ctrl->sdata[i2c->ctrl->cnt++];
      i2c->ctrl->snum--;
      if (i2c->ctrl->snum) {
        conset = I2C_CON_AA;
      }
      break;

    case I2C_STAT_SL_DT_NA:
      /* Data transmitted, no ACK received */
    case I2C_STAT_SL_LDT_A:
      /* Last data transmitted, ACK received */
    case I2C_STAT_SL_DR_NA:
      /* Data received, no ACK returned */
    case I2C_STAT_SL_DRGC_NA:
      /* Data recvd General call, no ACK returned */
    case I2C_STAT_SL_STOP:
      /* STOP received while addressed */
      i2c->ctrl->status.busy = 0;
      /* Slave operation completed, generate events */
      event = ARM_I2C_EVENT_TRANSFER_DONE;
      if (i2c->ctrl->status.arbitration_lost) {
        event |= ARM_I2C_EVENT_ARBITRATION_LOST;
      }
      if (i2c->ctrl->status.general_call) {
        event |= ARM_I2C_EVENT_GENERAL_CALL;
      }
      if (i2c->ctrl->snum) {
        event |= ARM_I2C_EVENT_TRANSFER_INCOMPLETE;
      }
      conset = i2c->ctrl->con_aa;
      break;
  }
  /* Set/clear control flags */
  i2c->reg->CONSET = conset;
  i2c->reg->CONCLR = conset ^ I2C_CON_FLAGS;

  return (event);
}