source: bootcd/isolinux/syslinux-6.03/core/graphics.c

/*
 * -----------------------------------------------------------------------
 *
 *   Copyright 1994-2008 H. Peter Anvin - All Rights Reserved
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
 *   Boston MA 02111-1307, USA; either version 2 of the License, or
 *   (at your option) any later version; incorporated herein by reference.
 *
 * -----------------------------------------------------------------------
 *
 * -----------------------------------------------------------------------
 *  VGA splash screen code
 * -----------------------------------------------------------------------
 */

#include <stddef.h>
#include "core.h"
#include <sys/io.h>
#include <hw/vga.h>
#include "fs.h"

#include "bios.h"
#include "graphics.h"
#include <syslinux/video.h>

__export uint8_t UsingVGA = 0;
uint16_t VGAPos;                /* Pointer into VGA memory */
__export uint16_t *VGAFilePtr;  /* Pointer into VGAFileBuf */
__export uint16_t VGAFontSize = 16;     /* Defaults to 16 byte font */

__export char VGAFileBuf[VGA_FILE_BUF_SIZE];    /* Unmangled VGA image name */
__export char VGAFileMBuf[FILENAME_MAX];        /* Mangled VGA image name */

static uint8_t VGARowBuffer[640 + 80];  /* Decompression buffer */
static uint8_t VGAPlaneBuffer[(640/8) * 4]; /* Plane buffers */

extern uint16_t GXPixCols;
extern uint16_t GXPixRows;

/* Maps colors to consecutive DAC registers */
static uint8_t linear_color[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8,
                                  9, 10, 11, 12, 13, 14, 15, 0 };

static FILE *fd;

typedef struct {
        uint32_t LSSMagic;      /* Magic number */
        uint16_t GraphXSize;    /* Width of splash screen file */
        uint16_t GraphYSize;    /* Height of splash screen file */
        uint8_t GraphColorMap[3*16];
} lssheader_t;

static lssheader_t LSSHeader;

#define LSSMagic        LSSHeader.LSSMagic
#define GraphXSize      LSSHeader.GraphXSize
#define GraphYSize      LSSHeader.GraphYSize

/*
 * Enable VGA graphics, if possible. Return 0 on success.
 */
static int vgasetmode(void)
{
        com32sys_t ireg, oreg;

        if (UsingVGA)
                return 0;               /* Nothing to do... */

        memset(&ireg, 0, sizeof(ireg));
        memset(&oreg, 0, sizeof(oreg));

        if (UsingVGA & 0x4) {
                /*
                 * We're in VESA mode, which means VGA; use VESA call
                 * to revert the mode, and then call the conventional
                 * mode-setting for good measure...
                 */
                ireg.eax.w[0] = 0x4F02;
                ireg.ebx.w[0] = 0x0012;
                __intcall(0x10, &ireg, &oreg);
        } else {
                /* Get video card and monitor */
                ireg.eax.w[0] = 0x1A00;
                __intcall(0x10, &ireg, &oreg);
                oreg.ebx.b[0] -= 7; /* BL=07h and BL=08h OK */

                if (oreg.ebx.b[0] > 1)
                        return -1;
        }

        /*
         * Set mode.
         */
        memset(&ireg, 0, sizeof(ireg));
        ireg.eax.w[0] = 0x0012; /* Set mode = 640x480 VGA 16 colors */
        __intcall(0x10, &ireg, &oreg);

        memset(&ireg, 0, sizeof(ireg));
        ireg.edx.w[0] = (uint32_t)linear_color;
        ireg.eax.w[0] = 0x1002; /* Write color registers */
        __intcall(0x10, &ireg, &oreg);

        UsingVGA = 1;

        /* Set GXPixCols and GXPixRows */
        GXPixCols = 640;
        GXPixRows = 480;

        use_font();
        ScrollAttribute = 0;

        return 0;
}

static inline char getnybble(void)
{
        char data = getc(fd);

        if (data & 0x10) {
                data &= 0x0F;
                return data;
        }

        data = getc(fd);
        return (data & 0x0F);
}

/*
 * rledecode:
 *      Decode a pixel row in RLE16 format.
 *
 * 'in': input (RLE16 encoded) buffer
 * 'out': output (decoded) buffer
 * 'count': pixel count
 */
static void rledecode(uint8_t *out, size_t count)
{
        uint8_t prev_pixel = 0;
        size_t size = count;
        uint8_t data;
        int i;

again:
        for (i = 0; i < size; i++) {

                data = getnybble();
                if (data == prev_pixel)
                        break;

                *out++ = data;
                prev_pixel = data;
        }

        size -= i;
        if (!size)
                return;

        /* Start of run sequence */
        data = getnybble();
        if (data == 0) {
                /* long run */
                uint8_t hi;

                data = getnybble();
                hi = getnybble();
                hi <<= 4;
                data |= hi;
                data += 16;
        }

        /* dorun */
        for (i = 0; i < data; i++)
                *out++ = prev_pixel;

        size -= i;
        if (size)
                goto again;
}

/*
 * packedpixel2vga:
 *      Convert packed-pixel to VGA bitplanes
 *
 * 'in': packed pixel string (640 pixels)
 * 'out': output (four planes @ 640/8 = 80 bytes)
 * 'count': pixel count (multiple of 8)
 */
static void packedpixel2vga(const uint8_t *in, uint8_t *out)
{
        int i, j, k;

        for (i = 0; i < 4; i++) {
                const uint8_t *ip = in;

                for (j = 0; j < 640/8; j++) {
                        uint8_t ob = 0;

                        for (k = 0; k < 8; k++) {
                                uint8_t px = *ip++;
                                ob = (ob << 1) | ((px >> i) & 1);
                        }

                        *out++ = ob;
                }
        }
}

/*
 * outputvga:
 *      Output four subsequent lines of VGA data
 *
 * 'in': four planes @ 640/8=80 bytes
 * 'out': pointer into VGA memory
 */
static void outputvga(const void *in, void *out)
{
        int i;

        /* Select the sequencer mask */
        outb(VGA_SEQ_IX_MAP_MASK, VGA_SEQ_ADDR);

        for (i = 1; i <= 8; i <<= 1) {
                /* Select the bit plane to write */
                outb(i, VGA_SEQ_DATA);
                memcpy(out, in, 640/8);
                in = (const char *)in + 640/8;
        }
}

/*
 * Display a graphical splash screen.
 */
__export void vgadisplayfile(FILE *_fd)
{
        char *p;
        int size;

        fd = _fd;

        /*
         * This is a cheap and easy way to make sure the screen is
         * cleared in case we were in graphics mode aready.
         */
        syslinux_force_text_mode();
        vgasetmode();

        size = 4+2*2+16*3;
        p = (char *)&LSSHeader;

        /* Load the header */
        while (size--)
                *p = getc(fd);

        if (*p != EOF) {
                com32sys_t ireg, oreg;
                uint16_t rows;
                int i;

                /* The header WILL be in the first chunk. */
                if (LSSMagic != 0x1413f33d)
                        return;

                memset(&ireg, 0, sizeof(ireg));

                /* Color map offset */
                ireg.edx.w[0] = offsetof(lssheader_t, GraphColorMap);

                ireg.eax.w[0] = 0x1012;        /* Set RGB registers */
                ireg.ebx.w[0] = 0;             /* First register number */
                ireg.ecx.w[0] = 16;            /* 16 registers */
                __intcall(0x10, &ireg, &oreg);

                /* Number of pixel rows */
                rows = (GraphYSize + VGAFontSize) - 1;
                rows = rows / VGAFontSize;
                if (rows >= VidRows)
                        rows = VidRows - 1;

                memset(&ireg, 0, sizeof(ireg));

                ireg.edx.b[1] = rows;
                ireg.eax.b[1] = 2;
                ireg.ebx.w[0] = 0;

                /* Set cursor below image */
                __intcall(0x10, &ireg, &oreg);

                rows = GraphYSize; /* Number of graphics rows */
                VGAPos = 0;

                for (i = 0; i < rows; i++) {
                        /* Pre-clear the row buffer */
                        memset(VGARowBuffer, 0, 640);

                        /* Decode one row */
                        rledecode(VGARowBuffer, GraphXSize);

                        packedpixel2vga(VGARowBuffer, VGAPlaneBuffer);
                        outputvga(VGAPlaneBuffer, MK_PTR(0xA000, VGAPos));
                        VGAPos += 640/8;
                }
        }
}

/*
 * Disable VGA graphics.
 */
__export void syslinux_force_text_mode(void)
{
        com32sys_t ireg, oreg;

        /* Already in text mode? */
        if (!UsingVGA)
                return;

        if (UsingVGA & 0x4) {
                /* VESA return to normal video mode */
                memset(&ireg, 0, sizeof(ireg));

                ireg.eax.w[0] = 0x4F02; /* Set SuperVGA video mode */
                ireg.ebx.w[0] = 0x0003;
                __intcall(0x10, &ireg, &oreg);
        }

        /* Return to normal video mode */
        memset(&ireg, 0, sizeof(ireg));
        ireg.eax.w[0] = 0x0003;
        __intcall(0x10, &ireg, &oreg);

        UsingVGA = 0;

        ScrollAttribute = 0x7;
        /* Restore text font/data */
        use_font();
}

static void vgacursorcommon(char data)
{
        if (UsingVGA) {
                com32sys_t ireg;
                memset(&ireg, 0, sizeof(ireg));

                ireg.eax.b[0] = data;
                ireg.eax.b[1] = 0x09;
                ireg.ebx.w[0] = 0x0007;
                ireg.ecx.w[0] = 1;
                __intcall(0x10, &ireg, NULL);
        }
}

void vgahidecursor(void)
{
        vgacursorcommon(' ');
}

void vgashowcursor(void)
{
        vgacursorcommon('_');
}

__export void using_vga(uint8_t vga, uint16_t pix_cols, uint16_t pix_rows)
{
    UsingVGA = vga;
    GXPixCols = pix_cols;
    GXPixRows = pix_rows;

    if (!(UsingVGA & 0x08))
        adjust_screen();
}

void pm_using_vga(com32sys_t *regs)
{
    using_vga(regs->eax.b[0], regs->ecx.w[0], regs->edx.w[0]);
}