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                 if (vector->trace)
  35                         printf("%s register vector %d (enabled %04x:%d)\n", __FUNCTION__, vector->vector, vector->enable.reg, vector->enable.bit);
  36
  37                 if (!vector->enable.reg)
  38                         printf("avr_register_vector: No 'enable' bit on vector %d !\n", vector->vector);
  39         }
  40 }
  41
  42 int avr_has_pending_interrupts(avr_t * avr)
  43 {
  44         return avr->pending[0] || avr->pending[1];
  45 }
  46
  47 int avr_is_interrupt_pending(avr_t * avr, avr_int_vector_t * vector)
  48 {
  49         return avr->pending[vector->vector >> 5] & (1 << (vector->vector & 0x1f));
  50 }
  51
  52 int avr_is_interrupt_enabled(avr_t * avr, avr_int_vector_t * vector)
  53 {
  54         return avr_regbit_get(avr, vector->enable);
  55 }
  56
  57 int avr_raise_interrupt(avr_t * avr, avr_int_vector_t * vector)
  58 {
  59         if (!vector || !vector->vector)
  60                 return 0;
  61         if (vector->trace)
  62                 printf("%s raising %d (enabled %d)\n", __FUNCTION__, vector->vector, avr_regbit_get(avr, vector->enable));
  63         // always mark the 'raised' flag to one, even if the interrupt is disabled
  64         // this allow "pooling" for the "raised" flag, like for non-interrupt
  65         // driven UART and so so. These flags are often "write one to clear"
  66         if (vector->raised.reg)
  67                 avr_regbit_set(avr, vector->raised);
  68
  69         // Mark the interrupt as pending
  70         avr->pending[vector->vector >> 5] |= (1 << (vector->vector & 0x1f));
  71         avr_raise_irq(&vector->irq, 1);
  72
  73         // If the interrupt is enabled, attempt to wake the core
  74         if (avr_regbit_get(avr, vector->enable)) {
  75                 if (!avr->pending_wait)
  76                         avr->pending_wait = 1;          // latency on interrupts ??
  77                 if (avr->state != cpu_Running) {
  78                         if (vector->trace)
  79                                 printf("Waking CPU due to interrupt\n");
  80                         avr->state = cpu_Running;       // in case we were sleeping
  81                 }
  82         }
  83         // return 'raised' even if it was already pending
  84         return 1;
  85 }
  86
  87 void avr_clear_interrupt(avr_t * avr, int v)
  88 {
  89         avr_int_vector_t * vector = avr->vector[v];
  90         avr->pending[v >> 5] &= ~(1 << (v & 0x1f));
  91         if (!vector)
  92                 return;
  93         if (vector->trace)
  94                 printf("%s cleared %d\n", __FUNCTION__, vector->vector);
  95         avr_raise_irq(&vector->irq, 0);
  96         if (vector->raised.reg)
  97                 avr_regbit_clear(avr, vector->raised);
  98 }
  99
 100 int avr_clear_interupt_if(avr_t * avr, avr_int_vector_t * vector, uint8_t old)
 101 {
 102         if (avr_regbit_get(avr, vector->raised)) {
 103                 avr_clear_interrupt(avr, vector->vector);
 104                 avr_regbit_clear(avr, vector->raised);
 105                 return 1;
 106         }
 107         avr_regbit_setto(avr, vector->raised, old);
 108         return 0;
 109 }
 110
 111 avr_irq_t * avr_get_interupt_irq(avr_t * avr, uint8_t v)
 112 {
 113         avr_int_vector_t * vector = avr->vector[v];
 114         return vector ? &vector->irq : NULL;
 115 }
 116
 117 /*
 118  * check wether interrupts are pending. I so, check if the interrupt "latency" is reached,
 119  * and if so triggers the handlers and jump to the vector.
 120  */
 121 void avr_service_interrupts(avr_t * avr)
 122 {
 123         if (!avr->sreg[S_I])
 124                 return;
 125
 126         if (avr_has_pending_interrupts(avr)) {
 127                 if (avr->pending_wait) {
 128                         avr->pending_wait--;
 129                         if (avr->pending_wait == 0) {
 130                                 int done = 0;
 131                                 for (int bi = 0; bi < 2 && !done; bi++) if (avr->pending[bi]) {
 132                                         for (int ii = 0; ii < 32 && !done; ii++)
 133                                                 if (avr->pending[bi] & (1 << ii)) {
 134
 135                                                         int v = (bi * 32) + ii; // vector
 136                                                         avr_int_vector_t * vector = avr->vector[v];
 137                                                         // if that single interupt is masked, ignore it and continue
 138                                                         if (vector && !avr_regbit_get(avr, vector->enable))
 139                                                                 continue;
 140                                                         if (vector && vector->trace)
 141                                                                 printf("%s calling %d\n", __FUNCTION__, v);
 142                                                         _avr_push16(avr, avr->pc >> 1);
 143                                                         avr->sreg[S_I] = 0;
 144                                                         avr->pc = v * avr->vector_size;
 145
 146                                                         avr_clear_interrupt(avr, v);
 147                                                         done++;
 148                                                         break;
 149                                                 }
 150                                         break;
 151                                 }
 152                         }
 153                 } else
 154                         avr->pending_wait = 2;  // for next one...
 155         }
 156 }
 157