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root / lab2 / timer.c @ 5

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#include <lcom/lcf.h>
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#include <lcom/timer.h>
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#include <stdint.h>
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#include "i8254.h"
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unsigned int count=0; //Initializing counter
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int hook_id = TIMER0_IRQ;
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int (timer_set_frequency)(uint8_t timer, uint32_t freq) {
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    if(freq<19){
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        return 1;
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    }
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    //freq=TIMER_FREQ/div, where TIMER_FREQ is the frequency of the clock and div os the value loaded nittially in the timer
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    uint16_t div = (TIMER_FREQ /freq);
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    uint8_t msb, lsb;
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    util_get_LSB(div,&lsb);         //getting LSB
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    util_get_MSB(div,&msb);         //getting MSB
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    uint8_t st;
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    if(timer_get_conf(timer,&st)==1){
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        printf("Error getting conf in frequency set\n");
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        return 1;
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    }
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    if(timer<0|timer>2){
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        printf("Error selecting timer in frequency set\n");
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        return 1;
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    }
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    else
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    {
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        if(timer==0){
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            st= ((st & 0x0F)|TIMER_LSB_MSB|TIMER_SEL0);             //The mask 0x0F is used so that the 4 LSBs are not changed
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            sys_outb(TIMER_CTRL,st);                                //Sends control word to program the timer
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            sys_outb(TIMER_0,lsb);
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            sys_outb(TIMER_0,msb);                                  //Both these functions program the timer
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        }
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        else if(timer==1){
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            st= ((st & 0x0F)|TIMER_LSB_MSB|TIMER_SEL1); 
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            sys_outb(TIMER_CTRL,st);                   
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            sys_outb(TIMER_1,lsb);
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            sys_outb(TIMER_1,msb);
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        }
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        else if(timer==2){
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            st= ((st & 0x0F)|TIMER_LSB_MSB|TIMER_SEL2); 
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            sys_outb(TIMER_CTRL,st);                   
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            sys_outb(TIMER_2,lsb);
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            sys_outb(TIMER_2,msb);
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        }
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    }
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  return 0;
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}
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int (timer_subscribe_int)(uint8_t *bit_no) {
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    *bit_no = BIT(hook_id);
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    if(sys_irqsetpolicy(TIMER0_IRQ,IRQ_REENABLE,&hook_id)==1){      //operation to subscribe int
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        printf("Error subscribing int\n");
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        return 1;
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    }
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  return 0;
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}
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int (timer_unsubscribe_int)() {
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  if(sys_irqrmpolicy(&hook_id)==1){
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      printf("Error unsubscribing int\n");
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      return 1;
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  }
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  return 0;
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}
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void (timer_int_handler)() {
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  count++;
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}
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int (timer_get_conf)(uint8_t timer, uint8_t *st) {
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    uint8_t read_back = (TIMER_RB_CMD | TIMER_RB_COUNT_ | TIMER_RB_SEL(timer)); //forming the read-back command (TIMER_RB_CMD (bit 7 and 6)
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                                                                                //TIMER_RB_COUNT (BIT 5) and TIMER_RB_SEL (bit timer+1)
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    if (sys_outb(TIMER_CTRL, read_back)==0) {                            //testing for an error
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        switch (timer) {
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            case 0:
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                if (util_sys_inb(TIMER_0, st)==1) {               //tests if TIMER_0 was chosen
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                    printf("Error selecting Timer 0\n");
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                    return 1;
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                }
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                break;
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            case 1:
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                if (util_sys_inb(TIMER_1, st)==1) {               //tests if TIMER_1 was chosen
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                    printf("Error selecting Timer 1\n");
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                    return 1;
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                }
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                break;
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            case 2:
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                if (util_sys_inb(TIMER_2, st)==1) {               //tests if TIMER_2 was chosen
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                    printf("Error selecting Timer 2\n");
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                    return 1;
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                }
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                break;
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            default:
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                printf("No clock selected\n");                                  //happens if timer<0 or timer>2
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                return 1;
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        }
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        return 0;
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    }
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    printf("Error in get config\n");
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    return 1;
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}
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int(timer_display_conf)(uint8_t timer, uint8_t st, enum timer_status_field field){
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    if(timer<0|timer>2){                                //tests for error in timer selection
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        printf("Error selecting timer\n");
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        return 1;
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    }
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    union timer_status_field_val config;                //create union (needed for the function at the end)
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    uint8_t aux;
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    aux=st;
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    switch(field){
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        case tsf_all:
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            config.byte=aux;
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            break;
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        case tsf_initial:                               //Checking init_mode (mask -> 0x30)
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            if((aux & 0x30)==TIMER_LSB){                //if 0x10
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                config.in_mode=LSB_only;
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            }
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            else if ((aux & 0x30)==TIMER_MSB){          //if 0x20
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                config.in_mode=MSB_only;
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            }
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            else if((aux & 0x30)==TIMER_LSB_MSB){       //if 0x30
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                config.in_mode=MSB_after_LSB;
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            }
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            else{
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                config.in_mode=INVAL_val;
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                printf("Invalid Initialization Mode\n");
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                return 1;
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            }
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            break;
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        case tsf_mode:                                  //Checking count_mode (mask -> 0x0E)
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            if((aux & 0x0E)==0){                        //if 0x00
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                config.count_mode=0;
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            }
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            else if((aux & 0x0E)==2){                   //if 0x02
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                config.count_mode=1;
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            }
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            else if((aux & 0x0E)==4|(aux & 0x0E)==12){  //if 0x04 or 0x0C
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                config.count_mode=2;
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            }
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            else if((aux & 0x0E)==6|(aux & 0x0E)==14){  //if 0x06 or 0x0E
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                config.count_mode=3;
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            }
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            else if((aux & 0x0E)==8){                   //if 0x08
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                config.count_mode=4;
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            }
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            else if((aux & 0x0E)==10){                  //if 0x0A
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                config.count_mode=5;
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            }
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            else{
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                printf("Error in checking counting mode\n");
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                return 1;
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            }
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            break;
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        case tsf_base:                                  //Checking bcd (mask -> 0x01)
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            if((aux & 0x01)== TIMER_BCD){
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                config.bcd = true;                      //if the last bit is 1, it's bcd
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            }
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            else if((aux & 0x01)==TIMER_BIN){
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                config.bcd = false;                     //if the last bit is 0, it's binary
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            }
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            else{
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                printf("Error in checking base\n");
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                return 1;
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            }
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            break;
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        default:
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            return 1;
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    }
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    if(timer_print_config(timer, field, config)==1){   //function that prints the result
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        printf("Error printing\n");
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        return 1;                                           
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    }
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    return 0;
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}