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 struct clock_ {
   9     DCPU16_WORD cycle_;
  10     DCPU16_WORD rate;
  11     DCPU16_WORD tick;
  12     DCPU16_WORD interrupt_message;
  13 };
  14
  15 static
  16 void clock_reset_(struct dcpu16 *vm, struct dcpu16_hw *hw) {
  17     struct clock_ *clock = (struct clock_ *)hw->data;
  18
  19     (void)vm;
  20
  21     memset(clock, 0, sizeof *clock);
  22 }
  23
  24 static
  25 void clock_cycle_(struct dcpu16 *vm, struct dcpu16_hw *hw) {
  26     struct clock_ *clock = (struct clock_ *)hw->data;
  27
  28     /* cycle is only called 100000 times per second */
  29     /* maximum rate is 60hz / word_max = 3932160 */
  30
  31     if (clock->rate == 0)
  32         return;
  33
  34     clock->cycle_++;
  35     if (clock->cycle_ >= clock->rate) {
  36         /* THIS CHECK IS WRONG, JUST A PLACEHOLDER */
  37         clock->cycle_ = 0;
  38         clock->tick += 1;
  39
  40         if (clock->interrupt_message) {
  41             if (dcpu16_interrupt(vm, clock->interrupt_message))
  42                 vm->warn_cb_("%s: could not send interrupt", hw->name_);
  43         }
  44     }
  45 }
  46
  47 static
  48 void clock_hwi_(struct dcpu16 *vm, struct dcpu16_hw *hw) {
  49     struct clock_ *clock = (struct clock_ *)hw->data;
  50     DCPU16_WORD reg_a = vm->reg[DCPU16_REG_A];
  51     DCPU16_WORD reg_b = vm->reg[DCPU16_REG_B];
  52
  53     switch (reg_a) {
  54         case 0: /* set tick gather rate, 60hz/B */
  55             clock->rate = reg_b;
  56             break;
  57
  58         case 1: /* fetch elapsed count since rate was set */
  59             vm->reg[DCPU16_REG_C] = clock->tick;
  60             break;
  61
  62         case 2:
  63             clock->interrupt_message = reg_b;
  64             break;
  65     }
  66 }
  67
  68 static
  69 int clock_data_init_(struct dcpu16_hw *hw, void *data) {
  70     (void)data;
  71
  72     hw->data = calloc(1, sizeof(struct clock_));
  73     if (hw->data == NULL) {
  74         hw->vm->warn_cb_("%s():%s", "calloc", strerror(errno));
  75         return -1;
  76     }
  77     return 0;
  78 }
  79
  80 static
  81 void clock_data_free_(struct dcpu16_hw *hw) {
  82     if (hw) {
  83         if (hw->data) {
  84             free(hw->data);
  85             hw->data = NULL;
  86         }
  87     }
  88 }
  89
  90 static struct dcpu16_hw hw_ = {
  91     .name_  = "Generic Clock (compatible)",
  92     .id_l   = 0xb402,
  93     .id_h   = 0x12d0,
  94     .ver    = 0x0001,
  95     .mfg_l  = 0x0000,
  96     .mfg_h  = 0x0000,
  97     .hwi    = clock_hwi_,
  98     .cycle  = clock_cycle_,
  99     .reset  = clock_reset_,
 100     .data   = (struct clock_ *)NULL
 101 };
 102
 103 struct dcpu16_hw_module dcpu16_hw_module_clock = {
 104     .template = &hw_,
 105     .data_init = clock_data_init_,
 106     .data_free = clock_data_free_,
 107 };