source: bootcd/isolinux/syslinux-6.03/com32/elflink/ldlinux/msg.c

#include <syslinux/video.h>
#include <com32.h>
#include <stdio.h>
#include <bios.h>
#include <graphics.h>

static uint8_t TextAttribute;   /* Text attribute for message file */
extern uint8_t DisplayMask;     /* Display modes mask */

/* Routine to interpret next print char */
static void (*NextCharJump)(uint8_t);

void msg_initvars(void);
static void msg_setfg(uint8_t data);
static void msg_putchar(uint8_t ch);

/*
 *
 * get_msg_file: Load a text file and write its contents to the screen,
 *               interpreting color codes.
 *
 * Returns 0 on success, -1 on failure.
 */
int get_msg_file(char *filename)
{
        FILE *f;
        char ch;

        f = fopen(filename, "r");
        if (!f)
                return -1;

        TextAttribute = 0x7;    /* Default grey on white */
        DisplayMask = 0x7;      /* Display text in all modes */
        msg_initvars();

        /*
         * Read the text file a byte at a time and interpret that
         * byte.
         */
        while ((ch = getc(f)) != EOF) {
                /* DOS EOF? */
                if (ch == 0x1A)
                        break;

                NextCharJump(ch);       /* Do what shall be done */
        }

        DisplayMask = 0x07;

        fclose(f);
        return 0;
}

static inline int display_mask_vga(void)
{
        uint8_t mask = UsingVGA & 0x1;
        return (DisplayMask & ++mask);
}

static void msg_setbg(uint8_t data)
{
        if (unhexchar(&data) == 0) {
                data <<= 4;
                if (display_mask_vga())
                        TextAttribute = data;

                NextCharJump = msg_setfg;
        } else {
                TextAttribute = 0x7;    /* Default attribute */
                NextCharJump = msg_putchar;
        }
}

static void msg_setfg(uint8_t data)
{
        if (unhexchar(&data) == 0) {
                if (display_mask_vga()) {
                        /* setbg set foreground to 0 */
                        TextAttribute |= data;
                }
        } else
                TextAttribute = 0x7;    /* Default attribute */

        NextCharJump = msg_putchar;
}

static inline void msg_ctrl_o(void)
{
        NextCharJump = msg_setbg;
}

/* Convert ANSI colors to PC display attributes */
static int convert_to_pcdisplay[] = { 0, 4, 2, 6, 1, 5, 3, 7 };

static void set_fgbg(void)
{
        uint8_t bg, fg;

        fg = convert_to_pcdisplay[(TextAttribute & 0x7)];
        bg = convert_to_pcdisplay[((TextAttribute >> 4) & 0x7)];

        printf("\033[");
        if (TextAttribute & 0x8)
                printf("1;"); /* Foreground bright */

        printf("3%dm\033[", fg);

        if (TextAttribute & 0x80)
                printf("5;"); /* Foreground blink */

        printf("4%dm", bg);
}

static void msg_formfeed(void)
{
        set_fgbg();
        printf("\033[2J\033[H\033[0m");
}

static void msg_novga(void)
{
        syslinux_force_text_mode();
        msg_initvars();
}

static void msg_viewimage(void)
{
        FILE *f;

        *VGAFilePtr = '\0';     /* Zero-terminate filename */

        mangle_name(VGAFileMBuf, VGAFileBuf);
        f = fopen(VGAFileMBuf, "r");
        if (!f) {
                /* Not there */
                NextCharJump = msg_putchar;
                return;
        }

        vgadisplayfile(f);
        fclose(f);
        msg_initvars();
}

/*
 * Getting VGA filename
 */
static void msg_filename(uint8_t data)
{
        /* <LF> = end of filename */
        if (data == 0x0A) {
                msg_viewimage();
                return;
        }

        /* Ignore space/control char */
        if (data > ' ') {
                if ((char *)VGAFilePtr < (VGAFileBuf + sizeof(VGAFileBuf)))
                        *VGAFilePtr++ = data;
        }
}

static void msg_vga(void)
{
        NextCharJump = msg_filename;
        VGAFilePtr = (uint16_t *)VGAFileBuf;
}

static void msg_normal(uint8_t data)
{
        /* 0x1 = text mode, 0x2 = graphics mode */
        if (!display_mask_vga() || !(DisplayCon & 0x01)) {
                /* Write to serial port */
                if (DisplayMask & 0x4)
                        write_serial(data);

                return;         /* Not screen */
        }

        set_fgbg();
        printf("%c\033[0m", data);
}

static void msg_modectl(uint8_t data)
{
        data &= 0x07;
        DisplayMask = data;
        NextCharJump = msg_putchar;
}

static void msg_putchar(uint8_t ch)
{
        /* 10h to 17h are mode controls */
        if (ch >= 0x10 && ch < 0x18) {
                msg_modectl(ch);
                return;
        }

        switch (ch) {
        case 0x0F:              /* ^O = color code follows */
                msg_ctrl_o();
                break;
        case 0x0D:              /* Ignore <CR> */
                break;
        case 0x0C:              /* <FF> = clear screen */
                msg_formfeed();
                break;
        case 0x19:              /* <EM> = return to text mode */
                msg_novga();
                break;
        case 0x18:              /* <CAN> = VGA filename follows */
                msg_vga();
                break;
        default:
                msg_normal(ch);
                break;
        }
}

/*
 * Subroutine to initialize variables, also needed after loading
 * graphics file.
 */
void msg_initvars(void)
{
        /* Initialize state machine */
        NextCharJump = msg_putchar;
}