Mercurial > repos > simple16

comparison src/timer.c @ 25:fb14515266f4

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Implemented timer and timer interrupts. Added get/setvbr instructions. Fixed assembler bug. Moved mnemonics into a separate source file
author Michael Pavone <pavone@retrodev.com>
date Thu, 31 Mar 2016 23:25:52 -0700
parents
children
comparison
equal deleted inserted replaced
24:4c9dbfa30a66 25:fb14515266f4
1 #include <stdint.h>
2 #include <string.h>
3 #include <limits.h>
4 #include "timer.h"
5
6 void timer_init(timer *context, uint32_t clock_div)
7 {
8 memset(context, 0, sizeof(timer));
9 context->clock_inc = clock_div;
10 }
11
12 void timer_run(timer *context, uint32_t target)
13 {
14 while (context->cycles < target)
15 {
16 if (context->current) {
17 context->current--;
18 if (!context->current) {
19 context->pending = 1;
20 }
21 } else {
22 context->current = context->load;
23 }
24 context->cycles += context->clock_inc;
25 }
26 }
27
28 uint32_t timer_next_interrupt(timer *context)
29 {
30 if (context->pending) {
31 return 0;
32 }
33 if (context->current) {
34 return context->cycles + context->current * context->clock_inc;
35 }
36 return UINT_MAX;
37 }
38
39 void timer_write(timer *context, uint16_t value)
40 {
41 context->load = context->current = value;
42 context->pending = 0;
43 }