Partial for TWI fixes (#137)

diff --git a/simavr/sim/avr_twi.c b/simavr/sim/avr_twi.c
index 5e351e5..521c03c 100644 (file)
--- a/simavr/sim/avr_twi.c
+++ b/simavr/sim/avr_twi.c
@@ -105,12 +105,22 @@ avr_twi_set_state_timer(
        return 0;
 }
 
+// Quick exponent helper for integer values > 0.
+static uint32_t _avr_twi_quick_exp(uint8_t base, uint8_t exp)
+{
+       uint32_t result = 1;
+       for (uint8_t i=exp; i>0; i--)
+               result *= base;
+       return result;
+}
+
 /*
  * This is supposed to trigger a timer whose duration is a multiple
  * of 'twi' clock cycles, which should be derived from the prescaler
  * (100khz, 400khz etc).
  * Right now it cheats and uses one twi cycle == one usec.
  */
+
 static void
 _avr_twi_delay_state(
                avr_twi_t * p,
@@ -118,9 +128,13 @@ _avr_twi_delay_state(
                uint8_t state)
 {
        p->next_twstate = state;
-       // TODO: calculate clock rate, convert to cycles, and use that
-       avr_cycle_timer_register_usec(
-                       p->io.avr, twi_cycles, avr_twi_set_state_timer, p);
+       uint8_t prescale = avr_regbit_get(p->io.avr, p->twps);
+       uint16_t bitrate =  p->io.avr->data[p->r_twbr];
+       uint32_t clockdiv = 16u+((bitrate<<1u)*_avr_twi_quick_exp(4,prescale));
+       //One TWI cycle is "clockdiv" AVR Cycles. So we can wait in these directly.
+       // printf("Waiting %d cycles\n",clockdiv*twi_cycles);
+       avr_cycle_timer_register(
+                       p->io.avr, twi_cycles*clockdiv, avr_twi_set_state_timer, p);
 }
 
 static void
@@ -309,14 +323,14 @@ avr_twi_write(
                                                p->state & TWI_COND_ACK ?
                                                                TWI_MRX_ADR_ACK : TWI_MRX_ADR_NACK);
                        } else {
-                               if(p->state & TWI_COND_WRITE){
+                               if(p->state & TWI_COND_ADDR){
                                        _avr_twi_delay_state(p, 0,
                                                        p->state & TWI_COND_ACK ?
-                                                                       TWI_MTX_DATA_ACK : TWI_MTX_DATA_NACK);
+                                                                       TWI_MTX_ADR_ACK : TWI_MTX_ADR_NACK);
                                }else{
                                        _avr_twi_delay_state(p, 9,
                                                        p->state & TWI_COND_ACK ?
-                                                                       TWI_MTX_ADR_ACK : TWI_MTX_ADR_NACK);
+                                                                       TWI_MTX_DATA_ACK : TWI_MTX_DATA_NACK);
                                }
                        }
                }