cm.c

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//cm.c - cursor and mouse stuff
#include "../lib/types.h"
#include "cm.h"
#include "vga.h"
#include "io.h"
#include "../lib/err.h"
 
/**
 * @brief cnb syncs current cursor vals too 2 ptrs of vars for them
 *
 * cnb is a function that gets the current cursors x and y position
 *
 * a common way to use it is
 * @code{.c}
 * #include "../io/cm.h" //or just cm.h
 * int cx, cy; //cursor x and cursor y
 * cnb(&cx, &cy);
 * @endcode 
 * 
 * @see cob()
*/
void __cnb(int* x, int* y) {
    outb(0x3D4, 0x0E); //select high byte cpu reg
    uint8_t hgh = inb(0x3D5); //read high byte
    outb(0x3D4, 0x0F); //select low byte now
    uint8_t low = inb(0x3D5);
 
    uint16_t pos = (hgh << 8) | low; //calculate position
    *x = pos % 80; //calculate x and y based of position
    *y = pos / 80;
}
 
/**
 * @brief cob exports cursor positions
 *
 * cob is a function that sets the cursor to a x and y position
 *
 * use cob with
 * @code{.c}
 * #include "../io/cm.h" //or just cm.h
 * cob(0, 0); //or your values
 * @endcode
 *
 * @warning when coding after running cob you must re-sync your cx and cy, DO NOT DO
 * @code{.c}
 * cnb(&cx, &cy);
 * cob(cx, cy + 1);
 * (rest of code)
 * @endcode
 * 
 * the rest of the code will still have the old cursor values and not be syncd, instead do
 * @code{.c}
 * cnb(&cx, &cy);
 * cob(cx, cy + 1);
 * cnb(&cx, &cy);
 * (rest of code)
 * @endcode
 *
 * this is good because the rest of your code will have up to date cursor positions
 *
 * @see cnb()
*/
void __cob(int x, int y) {
    if (y >= 25) {
        scrl();  //scroll if we're past bottom
        y = 24;
    }
    if (y < 0) y = 0; //clamps
    if (x >= 80) x = 79;
    if (x < 0) x = 0;
        
    uint16_t pos = (uint16_t)(y * 80 + x); //calculate pos based off given position
    
    outb(0x3D4, 0x0F); //request low byte
    outb(0x3D5, (uint8_t)(pos & 0xFF)); //write to data registry pos for low
    
    outb(0x3D4, 0x0E); //request high byte now
    outb(0x3D5, (uint8_t)((pos >> 8) & 0xFF)); //write data reg for high byte
}
 
/**
 * @brief scur shows the hardware text cursor
 *
 * scur is a function that enables the vga text cursor by writing
 * cursor start and end scanlines to the crtc registers
 *
 * using scur is done with
 * @code{.c}
 * #include "../io/cm.h" //or just cm.h
 * scur();
 * @endcode
 *
 * @see hcur(), cob()
 */
void __scur(void) {
    outb(0x3D4, 0x0A); //cursor start register
    outb(0x3D5, 0x06); //normal cursor (scanline 6 to 7)
    outb(0x3D4, 0x0B); //cursor end register
    outb(0x3D5, 0x07); //bottom scanline
}
 
/**
 * @brief hcur hides the hardware text cursor
 *
 * hcur is a function that disables the vga text cursor by setting
 * bit 5 of the cursor start register, making the cursor invisible
 *
 * using hcur is done with
 * @code{.c}
 * #include "../io/cm.h" //or just cm.h
 * hcur();
 * @endcode
 *
 * @see scur(), cob()
 */
void __hcur(void) {
    outb(0x3D4, 0x0A); //cursor start register
    outb(0x3D5, 0x20); //bit 5 = 1 disables cursor
}