git.squeep.com Git - dcpu16/blob - hw_clock.c

   1 #include <stdlib.h>
   2 #include <string.h>
   3 #include <errno.h>
   4
   5 #include "dcpu16.h"
   6 #include "hw_clock.h"
   7
   8 static dcpu16_hw_signal_t clock_reset_;
   9 static dcpu16_hw_signal_t clock_cycle_;
  10 static dcpu16_hw_signal_t clock_hwi_;
  11 static struct dcpu16_hw hw_ = {
  12     .name_  = "Generic Clock (compatible)",
  13     .id_l   = 0xb402,
  14     .id_h   = 0x12d0,
  15     .ver    = 0x0001,
  16     .mfg_l  = 0x0000,
  17     .mfg_h  = 0x0000,
  18     .hwi    = clock_hwi_,
  19     .cycle  = clock_cycle_,
  20     .reset  = clock_reset_,
  21     .data   = (struct clock_ *)NULL
  22 };
  23
  24 struct clock_ {
  25     DCPU16_WORD cycle_;
  26     DCPU16_WORD rate;
  27     DCPU16_WORD tick;
  28     DCPU16_WORD interrupt_message;
  29 };
  30
  31 static
  32 void clock_reset_(struct dcpu16 *vm, void *data) {
  33     struct clock_ *clock = (struct clock_ *)data;
  34
  35     (void)vm;
  36
  37     memset(clock, 0, sizeof *clock);
  38 }
  39
  40 static
  41 void clock_cycle_(struct dcpu16 *vm, void *data) {
  42     struct clock_ *clock = (struct clock_ *)data;
  43
  44     /* cycle is only called 100000 times per second */
  45     /* maximum rate is 60hz / word_max = 3932160 */
  46
  47     if (clock->rate == 0)
  48         return;
  49
  50     clock->cycle_++;
  51     if (clock->cycle_ >= clock->rate) {
  52         /* THIS CHECK IS WRONG, JUST A PLACEHOLDER */
  53         clock->cycle_ = 0;
  54         clock->tick += 1;
  55
  56         if (clock->interrupt_message) {
  57             if (dcpu16_interrupt(vm, clock->interrupt_message))
  58                 vm->warn_cb_("%s: could not send interrupt", hw_.name_);
  59         }
  60     }
  61 }
  62
  63 static
  64 void clock_hwi_(struct dcpu16 *vm, void *data) {
  65     struct clock_ *clock = (struct clock_ *)data;
  66     DCPU16_WORD reg_a = vm->reg[DCPU16_REG_A];
  67     DCPU16_WORD reg_b = vm->reg[DCPU16_REG_B];
  68
  69     switch (reg_a) {
  70         case 0: /* set tick gather rate, 60hz/B */
  71             clock->rate = reg_b;
  72             break;
  73
  74         case 1: /* fetch elapsed count since rate was set */
  75             vm->reg[DCPU16_REG_C] = clock->tick;
  76             break;
  77
  78         case 2:
  79             clock->interrupt_message = reg_b;
  80             break;
  81     }
  82 }
  83
  84 /* instantitate a new clock */
  85 struct dcpu16_hw *clock_new(struct dcpu16 *vm) {
  86     struct dcpu16_hw *hw;
  87
  88     hw = calloc(1, sizeof *hw);
  89     if (hw == NULL) {
  90         vm->warn_cb_("%s():%s", "calloc", strerror(errno));
  91         return NULL;
  92     }
  93     memcpy(hw, &hw_, sizeof *hw);
  94     hw->data = calloc(1, sizeof hw->data);
  95     if (hw->data == NULL) {
  96         vm->warn_cb_("%s():%s", "calloc", strerror(errno));
  97         free(hw);
  98         return NULL;
  99     }
 100
 101     return hw;
 102 }
 103
 104 void clock_del(struct dcpu16_hw **hw) {
 105     if (hw) {
 106         free((*hw)->data);
 107         (*hw)->data = NULL;
 108
 109         free((*hw));
 110         *hw = NULL;
 111     }
 112 }