git.rot13.org Git - simavr/blob - simavr/sim/sim_interrupts.c

   1 /*
   2         sim_interrupts.c
   3
   4         Copyright 2008, 2009 Michel Pollet <buserror@gmail.com>
   5
   6         This file is part of simavr.
   7
   8         simavr is free software: you can redistribute it and/or modify
   9         it under the terms of the GNU General Public License as published by
  10         the Free Software Foundation, either version 3 of the License, or
  11         (at your option) any later version.
  12
  13         simavr is distributed in the hope that it will be useful,
  14         but WITHOUT ANY WARRANTY; without even the implied warranty of
  15         MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16         GNU General Public License for more details.
  17
  18         You should have received a copy of the GNU General Public License
  19         along with simavr.  If not, see <http://www.gnu.org/licenses/>.
  20  */
  21
  22
  23 #include <stdlib.h>
  24 #include <stdio.h>
  25 #include <string.h>
  26 #include "sim_interrupts.h"
  27 #include "sim_core.h"
  28
  29 void avr_register_vector(avr_t *avr, avr_int_vector_t * vector)
  30 {
  31         if (vector->vector) {
  32                 vector->irq.irq = vector->vector;
  33                 avr->vector[vector->vector] = vector;
  34         }
  35 }
  36
  37 int avr_has_pending_interrupts(avr_t * avr)
  38 {
  39         return avr->pending[0] || avr->pending[1];
  40 }
  41
  42 int avr_is_interrupt_pending(avr_t * avr, avr_int_vector_t * vector)
  43 {
  44         return avr->pending[vector->vector >> 5] & (1 << (vector->vector & 0x1f));
  45 }
  46
  47 int avr_raise_interrupt(avr_t * avr, avr_int_vector_t * vector)
  48 {
  49         if (!vector || !vector->vector)
  50                 return 0;
  51         if (vector->trace)
  52                 printf("%s raising %d\n", __FUNCTION__, vector->vector);
  53         // always mark the 'raised' flag to one, even if the interrupt is disabled
  54         // this allow "pooling" for the "raised" flag, like for non-interrupt
  55         // driven UART and so so. These flags are often "write one to clear"
  56         if (vector->raised.reg)
  57                 avr_regbit_set(avr, vector->raised);
  58         if (vector->enable.reg) {
  59                 if (!avr_regbit_get(avr, vector->enable))
  60                         return 0;
  61         }
  62         if (!avr_is_interrupt_pending(avr, vector)) {
  63                 if (!avr->pending_wait)
  64                         avr->pending_wait = 2;          // latency on interrupts ??
  65                 avr->pending[vector->vector >> 5] |= (1 << (vector->vector & 0x1f));
  66                 avr_raise_irq(&vector->irq, 1);
  67
  68                 if (avr->state != cpu_Running) {
  69                         if (vector->trace)
  70                                 printf("Waking CPU due to interrupt\n");
  71                         avr->state = cpu_Running;       // in case we were sleeping
  72                 }
  73         }
  74         // return 'raised' even if it was already pending
  75         return 1;
  76 }
  77
  78 void avr_clear_interrupt(avr_t * avr, int v)
  79 {
  80         avr_int_vector_t * vector = avr->vector[v];
  81         avr->pending[v >> 5] &= ~(1 << (v & 0x1f));
  82         if (!vector)
  83                 return;
  84         if (vector->trace)
  85                 printf("%s cleared %d\n", __FUNCTION__, vector->vector);
  86         avr_raise_irq(&vector->irq, 0);
  87         if (vector->raised.reg)
  88                 avr_regbit_clear(avr, vector->raised);
  89 }
  90
  91 avr_irq_t * avr_get_interupt_irq(avr_t * avr, uint8_t v)
  92 {
  93         avr_int_vector_t * vector = avr->vector[v];
  94         return vector ? &vector->irq : NULL;
  95 }
  96
  97 /*
  98  * check wether interrupts are pending. I so, check if the interrupt "latency" is reached,
  99  * and if so triggers the handlers and jump to the vector.
 100  */
 101 void avr_service_interrupts(avr_t * avr)
 102 {
 103         if (!avr->sreg[S_I])
 104                 return;
 105
 106         if (avr_has_pending_interrupts(avr)) {
 107                 if (avr->pending_wait) {
 108                         avr->pending_wait--;
 109                         if (avr->pending_wait == 0) {
 110                                 int done = 0;
 111                                 for (int bi = 0; bi < 2 && !done; bi++) if (avr->pending[bi]) {
 112                                         for (int ii = 0; ii < 32 && !done; ii++)
 113                                                 if (avr->pending[bi] & (1 << ii)) {
 114
 115                                                         int v = (bi * 32) + ii; // vector
 116
 117                                                         if (avr->vector[v] && avr->vector[v]->trace)
 118                                                                 printf("%s calling %d\n", __FUNCTION__, v);
 119                                                         _avr_push16(avr, avr->pc >> 1);
 120                                                         avr->sreg[S_I] = 0;
 121                                                         avr->pc = v * avr->vector_size;
 122
 123                                                         avr_clear_interrupt(avr, v);
 124                                                         done++;
 125                                                         break;
 126                                                 }
 127                                         break;
 128                                 }
 129                         }
 130                 } else
 131                         avr->pending_wait = 2;  // for next one...
 132         }
 133 }
 134