gbasys

annotate src/timer.c @ 6:f77381b12726

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author John Tsiombikas <nuclear@member.fsf.org>
date Tue, 04 Sep 2012 05:05:50 +0300
parents
children 72c6429ae953
rev   line source
nuclear@0 1 /*
nuclear@0 2 Copyright 2004 John Tsiombikas <nuclear@siggraph.org>
nuclear@0 3
nuclear@0 4 This file is part of libgba, a library for GameBoy Advance development.
nuclear@0 5
nuclear@0 6 This program is free software; you can redistribute it and/or modify
nuclear@0 7 it under the terms of the GNU General Public License as published by
nuclear@0 8 the Free Software Foundation; either version 2 of the License, or
nuclear@0 9 (at your option) any later version.
nuclear@0 10
nuclear@0 11 This program is distributed in the hope that it will be useful,
nuclear@0 12 but WITHOUT ANY WARRANTY; without even the implied warranty of
nuclear@0 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
nuclear@0 14 GNU General Public License for more details.
nuclear@0 15
nuclear@0 16 You should have received a copy of the GNU General Public License
nuclear@0 17 along with this program; if not, write to the Free Software
nuclear@0 18 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
nuclear@0 19 */
nuclear@0 20
nuclear@0 21 #include <limits.h>
nuclear@0 22 #include "intr.h"
nuclear@0 23 #include "signal.h"
nuclear@0 24
nuclear@0 25 /* prescalar selection based on the system clock (16.78MHz) */
nuclear@0 26 #define TIMER_CNTL_CLK 0
nuclear@0 27 #define TIMER_CNTL_CLK64 1
nuclear@0 28 #define TIMER_CNTL_CLK256 2
nuclear@0 29 #define TIMER_CNTL_CLK1024 3
nuclear@0 30
nuclear@0 31 /* control bits */
nuclear@0 32 #define TIMER_CNTL_COUNTUP 4
nuclear@0 33 #define TIMER_CNTL_INTR 0x40
nuclear@0 34 #define TIMER_CNTL_ENABLE 0x80
nuclear@0 35
nuclear@0 36 static void timer_intr_handler(void);
nuclear@0 37
nuclear@0 38 volatile static unsigned short *reg_timer[] = {(void*)0x4000100, (void*)0x4000104, (void*)0x4000108, (void*)0x400010c};
nuclear@0 39 static unsigned short *reg_timer_cntl[] = {(void*)0x4000102, (void*)0x4000106, (void*)0x400010a, (void*)0x400010e};
nuclear@0 40
nuclear@0 41 static unsigned long milli_sec;
nuclear@0 42 static unsigned long alarm_val;
nuclear@0 43
nuclear@0 44 void enable_timer(int timer) {
nuclear@0 45 *reg_timer_cntl[timer] |= TIMER_CNTL_ENABLE;
nuclear@0 46 }
nuclear@0 47
nuclear@0 48 void disable_timer(int timer) {
nuclear@0 49 *reg_timer_cntl[timer] &= ~TIMER_CNTL_ENABLE;
nuclear@0 50 }
nuclear@0 51
nuclear@0 52 void reset_msec_timer(void) {
nuclear@0 53 *reg_timer_cntl[0] &= ~TIMER_CNTL_ENABLE;
nuclear@0 54 interrupt(INTR_TIMER0, timer_intr_handler);
nuclear@0 55 milli_sec = 0;
nuclear@0 56 *reg_timer[0] = USHRT_MAX - 16779;
nuclear@0 57 *reg_timer_cntl[0] = TIMER_CNTL_INTR | TIMER_CNTL_ENABLE;
nuclear@0 58 unmask(INTR_TIMER0);
nuclear@0 59 }
nuclear@0 60
nuclear@0 61
nuclear@0 62 unsigned long get_millisec(void) {
nuclear@0 63 return milli_sec;
nuclear@0 64 }
nuclear@0 65
nuclear@0 66 unsigned int alarm(unsigned int seconds) {
nuclear@0 67 unsigned int prev = alarm_val;
nuclear@0 68 alarm_val = seconds * 1000;
nuclear@0 69 }
nuclear@0 70
nuclear@0 71 static void timer_intr_handler(void) {
nuclear@0 72 milli_sec++;
nuclear@0 73
nuclear@0 74 if(alarm_val > 0) {
nuclear@0 75 if(!--alarm_val) raise(SIGALRM);
nuclear@0 76 }
nuclear@0 77 }