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         if (vector->trace)
  50                 printf("%s raising %d\n", __FUNCTION__, vector->vector);
  51         // always mark the 'raised' flag to one, even if the interrupt is disabled
  52         // this allow "pooling" for the "raised" flag, like for non-interrupt
  53         // driven UART and so so. These flags are often "write one to clear"
  54         if (vector->raised.reg)
  55                 avr_regbit_set(avr, vector->raised);
  56         if (vector->enable.reg) {
  57                 if (!avr_regbit_get(avr, vector->enable))
  58                         return 0;
  59         }
  60         if (!avr_is_interrupt_pending(avr, vector)) {
  61                 if (!avr->pending_wait)
  62                         avr->pending_wait = 2;          // latency on interrupts ??
  63                 avr->pending[vector->vector >> 5] |= (1 << (vector->vector & 0x1f));
  64
  65                 if (avr->state != cpu_Running) {
  66                         if (vector->trace)
  67                                 printf("Waking CPU due to interrupt\n");
  68                         avr->state = cpu_Running;       // in case we were sleeping
  69                 }
  70         }
  71         // return 'raised' even if it was already pending
  72         return 1;
  73 }
  74
  75 void avr_clear_interrupt(avr_t * avr, int v)
  76 {
  77         avr_int_vector_t * vector = avr->vector[v];
  78         avr->pending[v >> 5] &= ~(1 << (v & 0x1f));
  79         if (!vector)
  80                 return;
  81         if (vector->trace)
  82                 printf("%s cleared %d\n", __FUNCTION__, vector->vector);
  83         if (vector->raised.reg)
  84                 avr_regbit_clear(avr, vector->raised);
  85 }
  86
  87 /*
  88  * check wether interrupts are pending. I so, check if the interrupt "latency" is reached,
  89  * and if so triggers the handlers and jump to the vector.
  90  */
  91 void avr_service_interrupts(avr_t * avr)
  92 {
  93         if (!avr->sreg[S_I])
  94                 return;
  95
  96         if (avr_has_pending_interrupts(avr)) {
  97                 if (avr->pending_wait) {
  98                         avr->pending_wait--;
  99                         if (avr->pending_wait == 0) {
 100                                 int done = 0;
 101                                 for (int bi = 0; bi < 2 && !done; bi++) if (avr->pending[bi]) {
 102                                         for (int ii = 0; ii < 32 && !done; ii++)
 103                                                 if (avr->pending[bi] & (1 << ii)) {
 104
 105                                                         int v = (bi * 32) + ii; // vector
 106
 107                                                         if (avr->vector[v] && avr->vector[v]->trace)
 108                                                                 printf("%s calling %d\n", __FUNCTION__, v);
 109                                                         _avr_push16(avr, avr->pc >> 1);
 110                                                         avr->sreg[S_I] = 0;
 111                                                         avr->pc = v * avr->vector_size;
 112
 113                                                         avr_clear_interrupt(avr, v);
 114                                                         done++;
 115                                                         break;
 116                                                 }
 117                                         break;
 118                                 }
 119                         }
 120                 } else
 121                         avr->pending_wait = 2;  // for next one...
 122         }
 123 }
 124