gfx_driver_modex.c

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/* Mode X gfx driver
 * Mode X setting code derived from original Michael Abrash article in
 * Dr. Dobb's Journal/Graphics Programming Black Book
 */

#include "../fb_gfx.h"
#include "fb_gfx_dos.h"
#include "vga.h"
#include <pc.h>
#include <go32.h>
#include <sys/farptr.h>

static int driver_init(char *title, int w, int h, int depth, int refresh_rate, int flags);
static void driver_update(void);
static void end_of_driver_update(void);
static int *driver_fetch_modes(int depth, int *size);

GFXDRIVER fb_gfxDriverModeX =
{
        "ModeX",                 /* char *name; */
        driver_init,             /* int (*init)(char *title, int w, int h, int depth, int refresh_rate, int flags); */
        fb_dos_exit,             /* void (*exit)(void); */
        fb_dos_lock,             /* void (*lock)(void); */
        fb_dos_unlock,           /* void (*unlock)(void); */
        fb_dos_set_palette,      /* void (*set_palette)(int index, int r, int g, int b); */
        fb_dos_vga_wait_vsync,   /* void (*wait_vsync)(void); */
        fb_dos_get_mouse,        /* int (*get_mouse)(int *x, int *y, int *z, int *buttons, int *clip); */
        fb_dos_set_mouse,        /* void (*set_mouse)(int x, int y, int cursor, int clip); */
        fb_dos_set_window_title, /* void (*set_window_title)(char *title); */
        NULL,                    /* int (*set_window_pos)(int x, int y); */
        driver_fetch_modes,      /* int *(*fetch_modes)(int depth, int *size); */       
        NULL,                    /* void (*flip)(void); */
        NULL                     /* void (*poll_events)(void); */
};

static int modes[] = {
        SCREENLIST(320, 240),
        };

static unsigned short CRTParams[] = {
                                        0x0D06, /* vertical total */
                                        0x3E07, /* overflow (bit 8 of vertical counts) */
                                        0x4109, /* cell height (2 to double scan) */
                                        0xEA10, /* v sync start */
                                        0xAC11, /* v sync end and protect cr0-cr7 */
                                        0xDF12, /* vertical displayed */
                                        0x0014, /* turn off dword mode */
                                        0xE715, /* v blank start */
                                        0x0616, /* v blank end */
                                        0xE317  /* turn on byte mode */
                                        };

#define CRT_PARM_LENGTH 10

static int driver_init(char *title, int w, int h, int depth_arg, int refresh_rate, int flags)
{
    int depth = MAX(8, depth_arg);
        int i;
        
        fb_dos_detect();
        
        if (flags & DRIVER_OPENGL)
                return -1;
        
        if ((w != 320) || (h != 240) || (depth != 8)) {
                return -1;
        }
        
        /* set base video mode */
        fb_dos.regs.x.ax = 0x13;
        __dpmi_int(0x10, &fb_dos.regs);
        
        /* tweak to Mode X */
        outportw(SC_INDEX, 0x0604);  /* disable chain4 */
        
        outportw(SC_INDEX, 0x0100);  /* synchronous reset */
        outportb(MISC_OUTPUT, 0xE3); /* select 25 MHz dot clock & 60 Hz scanning rate */
        outportw(SC_INDEX, 0x0300);  /* undo reset (restart sequencer) */
        
        outportb(CRTC_INDEX, 0x11);  /* VSync End reg contains register write protect bit */
        outportb(CRTC_INDEX+1, inportb(CRTC_INDEX+1) & 0x7F);   /* remove write protect on various CRTC registers */
        
        for (i = 0; i < CRT_PARM_LENGTH; i++) {
                outportw(CRTC_INDEX, CRTParams[i]);
        }

        refresh_rate = 60;

        fb_dos.update = driver_update;
        fb_dos.update_len = (unsigned int)end_of_driver_update - (unsigned int)driver_update;
        fb_dos.set_palette = fb_dos_vga_set_palette;

        return fb_dos_init(title, w, h, depth, refresh_rate, flags);
}

static void driver_update(void)
{
        int plane;
        unsigned long screen;
        unsigned char *buffer;
        int x, y;
        
        _farsetsel(_dos_ds);
        for (plane = 0; plane < 4; plane++) {
                buffer = (unsigned char *)__fb_gfx->framebuffer + plane;
                outportw(SC_INDEX, (0x100 << plane) | 0x02);            /* set write plane */
                screen = 0xA0000;
                for (y = 0; y < fb_dos.h; y++) {
                        if (__fb_gfx->dirty[y]) {
                                for (x = 0; x < fb_dos.w; x += 4, screen++) {
                                        _farnspokeb(screen, buffer[x]);
                                }
                        } else {
                                screen += fb_dos.w / 4;
                        }
                        buffer += fb_dos.w;
                }
        }
}
static void end_of_driver_update(void) { /* do not remove */ }

static int *driver_fetch_modes(int depth, int *size)
{
        if (depth != 8) return NULL;
        
        *size = sizeof(modes) / sizeof(int);
        return memcpy((void*)malloc(sizeof(modes)), modes, sizeof(modes));
}