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                 avr->vector[vector->vector] = vector;
  33 }
  34
  35 int avr_has_pending_interrupts(avr_t * avr)
  36 {
  37         return avr->pending[0] || avr->pending[1];
  38 }
  39
  40 int avr_is_interrupt_pending(avr_t * avr, avr_int_vector_t * vector)
  41 {
  42         return avr->pending[vector->vector >> 5] & (1 << (vector->vector & 0x1f));
  43 }
  44
  45 int avr_raise_interrupt(avr_t * avr, avr_int_vector_t * vector)
  46 {
  47         if (!vector || !vector->vector)
  48                 return 0;
  49 //      printf("%s raising %d\n", __FUNCTION__, vector->vector);
  50         // always mark the 'raised' flag to one, even if the interuot is disabled
  51         // this allow "pooling" for the "raised" flag, like for non-interrupt
  52         // driven UART and so so. These flags are often "write one to clear"
  53         if (vector->raised.reg)
  54                 avr_regbit_set(avr, vector->raised);
  55         if (vector->enable.reg) {
  56                 if (!avr_regbit_get(avr, vector->enable))
  57                         return 0;
  58         }
  59         if (!avr_is_interrupt_pending(avr, vector)) {
  60                 if (!avr->pending_wait)
  61                         avr->pending_wait = 2;          // latency on interrupts ??
  62                 avr->pending[vector->vector >> 5] |= (1 << (vector->vector & 0x1f));
  63
  64                 if (avr->state != cpu_Running) {
  65                 //      printf("Waking CPU due to interrupt\n");
  66                         avr->state = cpu_Running;       // in case we were sleeping
  67                 }
  68         }
  69         // return 'raised' even if it was already pending
  70         return 1;
  71 }
  72
  73 void avr_clear_interrupt(avr_t * avr, int v)
  74 {
  75         avr_int_vector_t * vector = avr->vector[v];
  76         avr->pending[v >> 5] &= ~(1 << (v & 0x1f));
  77         if (!vector)
  78                 return;
  79 //      printf("%s cleared %d\n", __FUNCTION__, vector->vector);
  80         if (vector->raised.reg)
  81                 avr_regbit_clear(avr, vector->raised);
  82 }
  83
  84 /*
  85  * check wether interrupts are pending. I so, check if the interrupt "latency" is reached,
  86  * and if so triggers the handlers and jump to the vector.
  87  */
  88 void avr_service_interrupts(avr_t * avr)
  89 {
  90         if (!avr->sreg[S_I])
  91                 return;
  92
  93         if (avr_has_pending_interrupts(avr)) {
  94                 if (avr->pending_wait) {
  95                         avr->pending_wait--;
  96                         if (avr->pending_wait == 0) {
  97                                 int done = 0;
  98                                 for (int bi = 0; bi < 2 && !done; bi++) if (avr->pending[bi]) {
  99                                         for (int ii = 0; ii < 32 && !done; ii++)
 100                                                 if (avr->pending[bi] & (1 << ii)) {
 101
 102                                                         int v = (bi * 32) + ii; // vector
 103
 104                                                 //      printf("%s calling %d\n", __FUNCTION__, v);
 105                                                         _avr_push16(avr, avr->pc >> 1);
 106                                                         avr->sreg[S_I] = 0;
 107                                                         avr->pc = v * avr->vector_size;
 108
 109                                                         avr_clear_interrupt(avr, v);
 110                                                         done++;
 111                                                         break;
 112                                                 }
 113                                         break;
 114                                 }
 115                         }
 116                 } else
 117                         avr->pending_wait = 2;  // for next one...
 118         }
 119 }
 120