source: bootcd/isolinux/syslinux-6.03/com32/mboot/initvesa.c

/* ----------------------------------------------------------------------- *
 *
 *   Copyright 1999-2008 H. Peter Anvin - All Rights Reserved
 *   Copyright 2009 Intel Corporation; author: H. Peter Anvin
 *
 *   Permission is hereby granted, free of charge, to any person
 *   obtaining a copy of this software and associated documentation
 *   files (the "Software"), to deal in the Software without
 *   restriction, including without limitation the rights to use,
 *   copy, modify, merge, publish, distribute, sublicense, and/or
 *   sell copies of the Software, and to permit persons to whom
 *   the Software is furnished to do so, subject to the following
 *   conditions:
 *
 *   The above copyright notice and this permission notice shall
 *   be included in all copies or substantial portions of the Software.
 *
 *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 *   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 *   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 *   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 *   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 *   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 *   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 *   OTHER DEALINGS IN THE SOFTWARE.
 *
 * ----------------------------------------------------------------------- */

/*
 * initvesa.c
 *
 * Query the VESA BIOS and select a 640x480x32 mode with local mapping
 * support, if one exists.
 */

#include <inttypes.h>
#include <com32.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include <graphics.h>

#include "vesa.h"
#include "mboot.h"

struct vesa_info vesa_info;

void set_graphics_mode(const struct multiboot_header *mbh,
                       struct multiboot_info *mbi)
{
    com32sys_t rm;
    uint16_t mode, bestmode, *mode_ptr;
    struct vesa_general_info *gi;
    struct vesa_mode_info *mi;
    int pxf, bestpxf;
    int wantx, wanty;
    int err, besterr;
    bool better;
    addr_t viaddr;

    /* Only do this if requested by the OS image */
    if (!(mbh->flags & MULTIBOOT_VIDEO_MODE) || mbh->mode_type != 0)
        return;

    gi = lmalloc(sizeof *gi);
    if (!gi)
        return;

    mi = lmalloc(sizeof *mi);
    if (!mi)
        goto out;

    memset(&rm, 0, sizeof rm);
    memset(gi, 0, sizeof *gi);

    gi->signature = VBE2_MAGIC; /* Get VBE2 extended data */
    rm.eax.w[0] = 0x4F00;       /* Get SVGA general information */
    rm.edi.w[0] = OFFS(gi);
    rm.es = SEG(gi);
    __intcall(0x10, &rm, &rm);

    if (rm.eax.w[0] != 0x004F)
        goto out;               /* Function call failed */
    if (gi->signature != VESA_MAGIC)
        goto out;               /* No magic */
    if (gi->version < 0x0102)
        goto out;               /* VESA 1.2+ required */

    memcpy(&vesa_info.gi, gi, sizeof *gi);

    /* Search for a suitable mode with a suitable color and memory model... */

    mode_ptr = GET_PTR(gi->video_mode_ptr);
    bestmode = 0;
    bestpxf = 0;
    wantx = mbh->width  ? mbh->width  : 0xffff;
    wanty = mbh->height ? mbh->height : 0xffff;
    besterr = wantx + wanty;

    while ((mode = *mode_ptr++) != 0xFFFF) {
        mode &= 0x1FF;          /* The rest are attributes of sorts */

        memset(&rm, 0, sizeof rm);
        memset(mi, 0, sizeof *mi);
        rm.eax.w[0] = 0x4F01;   /* Get SVGA mode information */
        rm.ecx.w[0] = mode;
        rm.edi.w[0] = OFFS(mi);
        rm.es = SEG(mi);
        __intcall(0x10, &rm, &rm);

        /* Must be a supported mode */
        if (rm.eax.w[0] != 0x004f)
            continue;

        /* Must be an LFB color graphics mode supported by the hardware.

           The bits tested are:
           7 - linear frame buffer
           4 - graphics mode
           3 - color mode
           1 - mode information available (mandatory in VBE 1.2+)
           0 - mode supported by hardware
         */
        if ((mi->mode_attr & 0x009b) != 0x009b)
            continue;

        /* We don't support multibank (interlaced memory) modes */
        /*
         *  Note: The Bochs VESA BIOS (vbe.c 1.58 2006/08/19) violates the
         * specification which states that banks == 1 for unbanked modes;
         * fortunately it does report bank_size == 0 for those.
         */
        if (mi->banks > 1 && mi->bank_size)
            continue;

        /* Must either be a packed-pixel mode or a direct color mode
           (depending on VESA version ); must be a supported pixel format */

        if (mi->bpp == 32 &&
            (mi->memory_layout == 4 ||
             (mi->memory_layout == 6 && mi->rpos == 16 && mi->gpos == 8 &&
              mi->bpos == 0)))
            pxf = 32;
        else if (mi->bpp == 24 &&
                 (mi->memory_layout == 4 ||
                  (mi->memory_layout == 6 && mi->rpos == 16 && mi->gpos == 8 &&
                   mi->bpos == 0)))
            pxf = 24;
        else if (mi->bpp == 16 &&
                 (mi->memory_layout == 4 ||
                  (mi->memory_layout == 6 && mi->rpos == 11 && mi->gpos == 5 &&
                   mi->bpos == 0)))
            pxf = 16;
        else if (mi->bpp == 15 &&
                 (mi->memory_layout == 4 ||
                  (mi->memory_layout == 6 && mi->rpos == 10 && mi->gpos == 5 &&
                   mi->bpos == 0)))
            pxf = 15;
        else
            continue;

        better = false;
        err = abs(mi->h_res - wantx) + abs(mi->v_res - wanty);

#define IS_GOOD(mi, bestx, besty) \
        ((mi)->h_res >= (bestx) && (mi)->v_res >= (besty))

        if (!bestpxf)
            better = true;
        else if (!IS_GOOD(&vesa_info.mi, wantx, wanty) &&
                 IS_GOOD(mi, wantx, wanty))
            /* This matches criteria, which the previous one didn't */
            better = true;
        else if (IS_GOOD(&vesa_info.mi, wantx, wanty) &&
                 !IS_GOOD(mi, wantx, wanty))
            /* This doesn't match criteria, and the previous one did */
            better = false;
        else if (err < besterr)
            better = true;
        else if (err == besterr && (pxf == (int)mbh->depth || pxf > bestpxf))
            better = true;

        if (better) {
            bestmode = mode;
            bestpxf = pxf;
            memcpy(&vesa_info.mi, mi, sizeof *mi);
        }
    }

    if (!bestpxf)
        goto out;               /* No mode found */

    mi = &vesa_info.mi;
    mode = bestmode;

    /* Now set video mode */
    memset(&rm, 0, sizeof rm);
    rm.eax.w[0] = 0x4F02;       /* Set SVGA video mode */
    mode |= 0x4000;             /* Request linear framebuffer */
    rm.ebx.w[0] = mode;
    __intcall(0x10, &rm, &rm);
    if (rm.eax.w[0] != 0x004F)
        goto out;               /* Failed to set mode */

    mbi->flags |= MB_INFO_VIDEO_INFO;
    mbi->vbe_mode = mode;
    viaddr = map_data(&vesa_info, sizeof vesa_info, 4, 0);
    mbi->vbe_control_info = viaddr + offsetof(struct vesa_info, gi);
    mbi->vbe_mode_info = viaddr + offsetof(struct vesa_info, mi);

    /* Get the VBE 2.x PM entry point if supported */
    rm.eax.w[0] = 0x4F0A;
    rm.ebx.w[0] = 0;
    __intcall(0x10, &rm, &rm);
    if (rm.eax.w[0] == 0x004F) {
        mbi->vbe_interface_seg = rm.es;
        mbi->vbe_interface_off = rm.edi.w[0];
        mbi->vbe_interface_len = rm.ecx.w[0];
    }

    /* In theory this should be:
     *
     * UsingVga = (mi->mode_attr & 4) ? 0x0007 : 0x000f;
     *
     * However, that would assume all systems that claim to handle text
     * output in VESA modes actually do that...
     */
    graphics_using_vga(0x0F, vesa_info.mi.h_res, vesa_info.mi.v_res);

out:
    lfree(mi);
    lfree(gi);
}