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