/*      $NetBSD: vidc20config.c,v 1.37 2024/05/18 19:04:45 andvar Exp $ */

/*
 * Copyright (c) 2001 Reinoud Zandijk
 * Copyright (c) 1996 Mark Brinicombe
 * Copyright (c) 1996 Robert Black
 * Copyright (c) 1994-1995 Melvyn Tang-Richardson
 * Copyright (c) 1994-1995 RiscBSD kernel team
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the RiscBSD kernel team
 * 4. The name of the company nor the name of the author may be used to
 *    endorse or promote products derived from this software without specific
 *    prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE RISCBSD TEAM ``AS IS'' AND ANY EXPRESS
 * OR IMPLIED  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 *
 * NetBSD kernel project
 *
 * vidcvideo.c
 *
 * This file is the lower basis of the wscons driver for VIDC based ARM machines.
 * It features the initialisation and all VIDC writing and keeps in internal state
 * copy.
 * Its currently set up as a library file and not as a device; it could be named
 * vidcvideo0 eventually.
 */

#include <sys/cdefs.h>

__KERNEL_RCSID(0, "$NetBSD: vidc20config.c,v 1.37 2024/05/18 19:04:45 andvar Exp $");

#include <sys/types.h>
#include <sys/param.h>
#include <arm/iomd/vidc.h>
#include <machine/bootconfig.h>
#include <machine/intr.h>

#include <sys/systm.h>
#include <sys/device.h>
#include <uvm/uvm_extern.h>

#include <arm/iomd/iomdreg.h>
#include <arm/iomd/iomdvar.h>
#include <arm/iomd/vidc20config.h>

#define WriteWord(a, b) \
*((volatile unsigned int *)(a)) = (b)

#define ReadWord(a) \
(*((volatile unsigned int *)(a)))

/*
 * A structure containing ALL the information required to restore
 * the VIDC20 to any given state.  ALL vidc transactions should
 * go through these procedures, which record the vidc's state.
 * it may be an idea to set the permissions of the vidc base address
 * so we get a fault, so the fault routine can record the state but
 * I guess that's not really necessary for the time being, since we
 * can make the kernel more secure later on.  Also, it is possible
 * to write a routine to allow 'reading' of the vidc registers.
 */

static struct vidc_state vidc_lookup = {        
        { 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
          0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
          0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
          0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
          0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
          0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
          0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
          0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0
        },

        VIDC_PALREG,
        VIDC_BCOL,
        VIDC_CP1 ,
        VIDC_CP2,
        VIDC_CP3,
        VIDC_HCR,
        VIDC_HSWR,
        VIDC_HBSR,
        VIDC_HDSR,
        VIDC_HDER,
        VIDC_HBER,
        VIDC_HCSR,
        VIDC_HIR,
        VIDC_VCR,
        VIDC_VSWR,
        VIDC_VBSR,
        VIDC_VDSR,
        VIDC_VDER,
        VIDC_VBER,
        VIDC_VCSR,
        VIDC_VCER,
        VIDC_EREG,
        VIDC_FSYNREG,
        VIDC_CONREG,
        VIDC_DCTL
};

struct vidc_state vidc_current[1];


/*
 * XXX global display variables XXX ... should be a structure
 */
static int cold_init = 0;               /* flags initialisation */
extern videomemory_t videomemory;

static struct vidc_mode vidc_currentmode;

unsigned int dispstart;
unsigned int dispsize;
unsigned int dispbase;
unsigned int dispend;
unsigned int ptov;
unsigned int vmem_base;
unsigned int phys_base;
unsigned int transfersize;


/* cursor stuff */
char *cursor_normal;
char *cursor_transparent;
int   p_cursor_normal;
int   p_cursor_transparent;
int   cursor_width;
int   cursor_height;


/*
 * VIDC mode definitions
 * generated from RISC OS mode definition file by an `awk' script
 */
extern const struct videomode vidc_videomode_list[];
extern const int vidc_videomode_count;


/*
 * configuration printing
 *
 */

void
vidcvideo_printdetails(void)
{
        printf(": refclk=%dMHz %dKB %s ", (vidc_fref / 1000000),
            videomemory.vidm_size / 1024,
            (videomemory.vidm_type == VIDEOMEM_TYPE_VRAM) ? "VRAM" : "DRAM");
}


/*
 * Common functions to directly access VIDC registers
 */
int
vidcvideo_write(u_int reg, int value)
{
        int counter;

        int *current;
        int *tab;

        tab     = (int *)&vidc_lookup;
        current = (int *)vidc_current; 


        /*
         * OK, the VIDC_PALETTE register is handled differently
         * to the others on the VIDC, so take that into account here
         */
        if (reg == VIDC_PALREG) {
                vidc_current->palreg = 0;
                WriteWord(vidc_base, reg | value);
                return 0;
        }

        if (reg == VIDC_PALETTE) {
                WriteWord(vidc_base, reg | value);
                vidc_current->palette[vidc_current->palreg] = value;
                vidc_current->palreg++;
                vidc_current->palreg = vidc_current->palreg & 0xff;
                return 0;
        }

        /*
         * Undefine SAFER if you wish to speed things up (a little)
         * although this means the function will assume things about
         * the structure of vidc_state. i.e. the first 256 words are
         * the palette array
         */

#define SAFER

#ifdef  SAFER
#define INITVALUE 0
#else
#define INITVALUE 256
#endif

        for (counter = INITVALUE;
             counter <= sizeof(struct vidc_state);
             counter++) {
                if (reg == tab[counter]) {
                        WriteWord ( vidc_base, reg | value );
                        current[counter] = value;
                        return 0;
                }
        }
        return -1;
}


void
vidcvideo_setpalette(struct vidc_state *vidc)
{
        int counter = 0;

        vidcvideo_write(VIDC_PALREG, 0x00000000);
        for (counter = 0; counter <= 255; counter++)
                vidcvideo_write(VIDC_PALETTE, vidc->palette[counter]);
}


void
vidcvideo_setstate(struct vidc_state *vidc)
{
        vidcvideo_write ( VIDC_PALREG,          vidc->palreg    );
        vidcvideo_write ( VIDC_BCOL,            vidc->bcol      );
        vidcvideo_write ( VIDC_CP1,             vidc->cp1       );
        vidcvideo_write ( VIDC_CP2,             vidc->cp2       );
        vidcvideo_write ( VIDC_CP3,             vidc->cp3       );
        vidcvideo_write ( VIDC_HCR,             vidc->hcr       );
        vidcvideo_write ( VIDC_HSWR,            vidc->hswr      );
        vidcvideo_write ( VIDC_HBSR,            vidc->hbsr      );
        vidcvideo_write ( VIDC_HDSR,            vidc->hdsr      );
        vidcvideo_write ( VIDC_HDER,            vidc->hder      );
        vidcvideo_write ( VIDC_HBER,            vidc->hber      );
        vidcvideo_write ( VIDC_HCSR,            vidc->hcsr      );
        vidcvideo_write ( VIDC_HIR,             vidc->hir       );
        vidcvideo_write ( VIDC_VCR,             vidc->vcr       );
        vidcvideo_write ( VIDC_VSWR,            vidc->vswr      );
        vidcvideo_write ( VIDC_VBSR,            vidc->vbsr      );
        vidcvideo_write ( VIDC_VDSR,            vidc->vdsr      );
        vidcvideo_write ( VIDC_VDER,            vidc->vder      );
        vidcvideo_write ( VIDC_VBER,            vidc->vber      );
        vidcvideo_write ( VIDC_VCSR,            vidc->vcsr      );
        vidcvideo_write ( VIDC_VCER,            vidc->vcer      );
/*
 * Right, dunno what to set these to yet, but let's keep RiscOS's
 * ones for now, until the time is right to finish this code
 */     

/*      vidcvideo_write ( VIDC_EREG,            vidc->ereg      );      */
/*      vidcvideo_write ( VIDC_FSYNREG, vidc->fsynreg   );      */
/*      vidcvideo_write ( VIDC_CONREG,  vidc->conreg    );      */
/*      vidcvideo_write ( VIDC_DCTL,            vidc->dctl      );      */

        vidcvideo_setpalette(vidc);
}


void
vidcvideo_getstate(struct vidc_state *vidc)
{

        *vidc = *vidc_current;
}


void
vidcvideo_getmode(struct vidc_mode *mode)
{

        *mode = vidc_currentmode;
}


static int
vidcvideo_coldinit(void)
{
        struct videomode const *modes;
        unsigned besterror;
        int count;
        int i;
        unsigned framerate;

        /* Blank out the cursor */

        vidcvideo_write(VIDC_CP1, 0x0);
        vidcvideo_write(VIDC_CP2, 0x0);
        vidcvideo_write(VIDC_CP3, 0x0);

        dispbase = vmem_base = dispstart = videomemory.vidm_vbase;
        phys_base = videomemory.vidm_pbase;

        /* Nut - should be using videomemory.vidm_size - mark */
        if (videomemory.vidm_type == VIDEOMEM_TYPE_DRAM) {
                dispsize = videomemory.vidm_size;
                transfersize = 16;
        } else {
                dispsize = bootconfig.vram[0].pages * PAGE_SIZE;
                transfersize = dispsize >> 10;
        }
    
        ptov = dispbase - phys_base;

        dispend = dispstart+dispsize;

        if (vidc_videomode_count > 0) {
                modes = vidc_videomode_list;
                count = vidc_videomode_count;
        } else {
                modes = videomode_list;
                count = videomode_count;
        }

        /* try to find the current mode from the bootloader in my table */ 
        vidc_currentmode.timings = modes[0];
        besterror = 1000000;
        for (i = 0; i < count; i++) {
                /* We don't support interlace or doublescan */
                if (modes[i].flags & (VID_INTERLACE | VID_DBLSCAN))
                        continue;
                /*
                 * We jump through a few hoops here to ensure that we
                 * round roughly to the nearest integer without too
                 * much danger of overflow.
                 */
                framerate = (modes[i].dot_clock * 1000 /
                    modes[i].htotal * 2 / modes[i].vtotal + 1) / 2;
                if (modes[i].hdisplay == bootconfig.width + 1
                    && modes[i].vdisplay == bootconfig.height + 1
                    && abs(framerate - bootconfig.framerate) < besterror) {
                        vidc_currentmode.timings = modes[i];
                        besterror = abs(framerate - bootconfig.framerate);
                }
        }

        vidc_currentmode.log2_bpp = bootconfig.log2_bpp;

        dispstart = dispbase;
        dispend = dispstart+dispsize;

        IOMD_WRITE_WORD(IOMD_VIDINIT, dispstart-ptov);
        IOMD_WRITE_WORD(IOMD_VIDSTART, dispstart-ptov);
        IOMD_WRITE_WORD(IOMD_VIDEND, (dispend-transfersize)-ptov);
        return 0;
}


/* simple function to abstract vidc variables ; returns virt start address of screen */
/* XXX assumption that video memory is mapped in twice */
void *vidcvideo_hwscroll(int bytes)
{

        dispstart += bytes;
        if (dispstart >= dispbase + dispsize) dispstart -= dispsize;
        if (dispstart <  dispbase)            dispstart += dispsize;
        dispend = dispstart+dispsize;

        /* return the start of the bit map of the screen (left top) */
        return (void *)dispstart;
}


/* reset the HW scroll to be at the start for the benefit of f.e. X */
void *vidcvideo_hwscroll_reset(void)
{
        void *cookie = (void *)dispstart;

        dispstart = dispbase;
        dispend = dispstart + dispsize;
        return cookie;
}


/* put HW scroll back to where it was */
void *vidcvideo_hwscroll_back(void *cookie)
{

        dispstart = (int)cookie;
        dispend = dispstart + dispsize;
        return cookie;
}


/* this function is to be called preferably at vsync */
void vidcvideo_progr_scroll(void)
{

        IOMD_WRITE_WORD(IOMD_VIDINIT, dispstart-ptov);
        IOMD_WRITE_WORD(IOMD_VIDSTART, dispstart-ptov);
        IOMD_WRITE_WORD(IOMD_VIDEND, (dispend-transfersize)-ptov);
}


/*
 * Select a new mode by reprogramming the VIDC chip
 * XXX this part is known not to work for 32bpp
 */

struct vidc_mode newmode;

static const int bpp_mask_table[] = {
        0,  /* 1bpp */
        1,  /* 2bpp */
        2,  /* 4bpp */
        3,  /* 8bpp */
        4,  /* 16bpp */
        6   /* 32bpp */
};


void
vidcvideo_setmode(struct vidc_mode *mode)
{    
        struct videomode *vm;
        int bpp_mask;
        int ereg;
        int best_r, best_v;
        int least_error;
        int r, v, f;

        /*
         * Find out what bit mask we need to or with the vidc20
         * control register in order to generate the desired number of
         * bits per pixel.  log_bpp is log base 2 of the number of
         * bits per pixel.
         */

        bpp_mask = bpp_mask_table[mode->log2_bpp];

        vidc_currentmode = *mode;
        vm = &vidc_currentmode.timings;

        least_error = INT_MAX;
        best_r = 0; best_v = 0;

        for (v = 63; v > 0; v--) {
                for (r = 63; r > 0; r--) {
                        f = ((v * vidc_fref) /1000) / r;
                        if (least_error >= abs(f - vm->dot_clock)) {
                                least_error =  abs(f - vm->dot_clock);
                                best_r = r;
                                best_v = v;
                        }
                }
        }

        if (best_r > 63) best_r=63;
        if (best_v > 63) best_v=63;
        if (best_r < 1)  best_r= 1;
        if (best_v < 1)  best_v= 1;

        vidcvideo_write(VIDC_FSYNREG, (best_v-1)<<8 | (best_r-1)<<0);

        /*
         * The translation from struct videomode to VIDC timings is made
         * fun by the fact that the VIDC counts from the start of the sync
         * pulse while struct videomode counts from the start of the display.
         */
        vidcvideo_write(VIDC_HSWR, (vm->hsync_end - vm->hsync_start - 8) & ~1);
        vidcvideo_write(VIDC_HBSR, (vm->htotal - vm->hsync_start - 12) & ~1);
        vidcvideo_write(VIDC_HDSR, (vm->htotal - vm->hsync_start - 18) & ~1);
        vidcvideo_write(VIDC_HDER,
            (vm->htotal - vm->hsync_start + vm->hdisplay - 18) & ~1);
        vidcvideo_write(VIDC_HBER,
            (vm->htotal - vm->hsync_start + vm->hdisplay - 12) & ~1);
        vidcvideo_write(VIDC_HCR, (vm->htotal - 8) & ~3);

        vidcvideo_write(VIDC_VSWR, vm->vsync_end - vm->vsync_start - 1);
        vidcvideo_write(VIDC_VBSR, vm->vtotal - vm->vsync_start - 1);
        vidcvideo_write(VIDC_VDSR, vm->vtotal - vm->vsync_start - 1);
        vidcvideo_write(VIDC_VDER,
            vm->vtotal - vm->vsync_start + vm->vdisplay - 1);
        vidcvideo_write(VIDC_VBER,
            vm->vtotal - vm->vsync_start + vm->vdisplay - 1);
        /* XXX VIDC20 data sheet say to subtract 2 */
        vidcvideo_write(VIDC_VCR, vm->vtotal - 1);

        IOMD_WRITE_WORD(IOMD_FSIZE, vm->vtotal - vm->vdisplay - 1);

        if (dispsize <= 1024*1024)
                vidcvideo_write(VIDC_DCTL, vm->hdisplay>>2 | 1<<16 | 1<<12);
        else
                vidcvideo_write(VIDC_DCTL, vm->hdisplay>>2 | 3<<16 | 1<<12);

        ereg = 1<<12;
        if (vm->flags & VID_NHSYNC)
                ereg |= 1<<16;
        if (vm->flags & VID_NVSYNC)
                ereg |= 1<<18;
        vidcvideo_write(VIDC_EREG, ereg);

        /*
         * Set the video FIFO preload value and bit depth.  Chapter 6
         * of the VIDC20 Data Sheet has full details of the FIFO
         * preload, but we don't do anything clever and just use the
         * largest possible value, which is 7 when the VIDC20 is in
         * 32-bit mode (0MB or 1MB VRAM) and 6 when it is in 64-bit
         * mode (2MB VRAM).
         */
        if (dispsize > 1024*1024)
                vidcvideo_write(VIDC_CONREG, 6<<8 | bpp_mask<<5);
        else
                vidcvideo_write(VIDC_CONREG, 7<<8 | bpp_mask<<5);
}


#if 0
/* not used for now */
void
vidcvideo_set_display_base(u_int base)
{
        dispstart = dispstart-dispbase + base;
        dispbase = vmem_base = base;
        dispend = base + dispsize;
        ptov = dispbase - phys_base;
}
#endif


/*
 * Main initialisation routine for now
 */

static int cursor_init = 0;

int
vidcvideo_init(void)
{
        vidcvideo_coldinit();
        if (cold_init && (cursor_init == 0)) 
                /*      vidcvideo_flash_go() */;

        /* setting a mode goes wrong in 32 bpp ... 8 and 16 seem OK */
        vidcvideo_setmode(&vidc_currentmode);
        vidcvideo_blank(0);                     /* display on */

        vidcvideo_stdpalette();

        if (cold_init == 0) {
                vidcvideo_write(VIDC_CP1, 0x0);
                vidcvideo_write(VIDC_CP2, 0x0);
                vidcvideo_write(VIDC_CP3, 0x0);
        } else
                vidcvideo_cursor_init(CURSOR_MAX_WIDTH, CURSOR_MAX_HEIGHT);

        cold_init = 1;
        return 0;
}


/* reinitialise the vidcvideo */
void
vidcvideo_reinit(void)
{

        vidcvideo_coldinit();
        vidcvideo_setmode(&vidc_currentmode);
}


int
vidcvideo_cursor_init(int width, int height)
{
        static char *cursor_data = NULL;
        int counter;
        int line;
        paddr_t pa;

        cursor_width  = width;
        cursor_height = height;

        if (!cursor_data) {
                /* Allocate cursor memory first time round */
                cursor_data = (char *)uvm_km_alloc(kernel_map, PAGE_SIZE, 0,
                    UVM_KMF_WIRED | UVM_KMF_ZERO);
                if (!cursor_data)
                        panic("Cannot allocate memory for hardware cursor");
                (void) pmap_extract(pmap_kernel(), (vaddr_t)cursor_data, &pa);
                IOMD_WRITE_WORD(IOMD_CURSINIT, pa);
        }

        /* Blank the cursor while initialising its sprite */

        vidcvideo_write ( VIDC_CP1, 0x0 );
        vidcvideo_write ( VIDC_CP2, 0x0 );
        vidcvideo_write ( VIDC_CP3, 0x0 );

        cursor_normal       = cursor_data;
        cursor_transparent  = cursor_data + (height * width);

        cursor_transparent += 32;                                       /* ALIGN */
        cursor_transparent = (char *)((int)cursor_transparent & (~31) );

        for ( line = 0; line<height; ++line ) {
                for ( counter=0; counter<width/4;counter++ )
                        cursor_normal[line * width + counter]=0x55;             /* why 0x55 ? */
                for ( ; counter<8; counter++ )
                        cursor_normal[line * width + counter]=0;
        }

        for ( line = 0; line<height; ++line ) {
                for ( counter=0; counter<width/4;counter++ )
                        cursor_transparent[line * width + counter]=0x00;
                for ( ; counter<8; counter++ )
                        cursor_transparent[line * width + counter]=0;
        }


        (void) pmap_extract(pmap_kernel(), (vaddr_t)cursor_normal,
            (void *)&p_cursor_normal);
        (void) pmap_extract(pmap_kernel(), (vaddr_t)cursor_transparent,
            (void *)&p_cursor_transparent);

        memset(cursor_normal, 0x55, width*height);              /* white? */
        memset(cursor_transparent, 0x00, width*height);/* to see the diffence */

        /* Ok, now program the cursor; should be blank */
        vidcvideo_enablecursor(0);

        return 0;
}


void
vidcvideo_updatecursor(int xcur, int ycur)
{
        int frontporch = vidc_currentmode.timings.htotal -
            vidc_currentmode.timings.hsync_start;
        int topporch   =  vidc_currentmode.timings.vtotal -
            vidc_currentmode.timings.vsync_start;

        vidcvideo_write(VIDC_HCSR, frontporch -17 + xcur);
        vidcvideo_write(VIDC_VCSR, topporch   -2  + (ycur+1)-2 + 3 -
            cursor_height);
        vidcvideo_write(VIDC_VCER, topporch   -2  + (ycur+3)+2 + 3 );
}


void
vidcvideo_enablecursor(int on)
{

        if (on)
                IOMD_WRITE_WORD(IOMD_CURSINIT,p_cursor_normal);
        else
                IOMD_WRITE_WORD(IOMD_CURSINIT,p_cursor_transparent);
        vidcvideo_write ( VIDC_CP1, 0xffffff );         /* enable */
}


void
vidcvideo_stdpalette(void)
{
        int i;

        switch (vidc_currentmode.log2_bpp) {
        case 0: /* 1 bpp */
        case 1: /* 2 bpp */
        case 2: /* 4 bpp */
        case 3: /* 8 bpp */
                vidcvideo_write(VIDC_PALREG, 0x00000000);
                vidcvideo_write(VIDC_PALETTE, VIDC_COL(  0,   0,   0));  
                vidcvideo_write(VIDC_PALETTE, VIDC_COL(255,   0,   0));
                vidcvideo_write(VIDC_PALETTE, VIDC_COL(  0, 255,   0));
                vidcvideo_write(VIDC_PALETTE, VIDC_COL(255, 255,   0));
                vidcvideo_write(VIDC_PALETTE, VIDC_COL(  0,   0, 255));
                vidcvideo_write(VIDC_PALETTE, VIDC_COL(255,   0, 255));
                vidcvideo_write(VIDC_PALETTE, VIDC_COL(  0, 255, 255));
                vidcvideo_write(VIDC_PALETTE, VIDC_COL(255, 255, 255));
                vidcvideo_write(VIDC_PALETTE, VIDC_COL(128, 128, 128));
                vidcvideo_write(VIDC_PALETTE, VIDC_COL(255, 128, 128));
                vidcvideo_write(VIDC_PALETTE, VIDC_COL(128, 255, 128));
                vidcvideo_write(VIDC_PALETTE, VIDC_COL(255, 255, 128));
                vidcvideo_write(VIDC_PALETTE, VIDC_COL(128, 128, 255));
                vidcvideo_write(VIDC_PALETTE, VIDC_COL(255, 128, 255));
                vidcvideo_write(VIDC_PALETTE, VIDC_COL(255, 255, 255));
                break;
        case 4: /* 16 bpp */
                /*
                 * The use of the palette in 16-bit modes is quite
                 * fun.  Comments in linux/drivers/video/acornfb.c
                 * imply that it goes something like this:
                 *
                 * red   = LUT[pixel[7:0]].red
                 * green = LUT[pixel[11:4]].green
                 * blue  = LUT[pixel[15:8]].blue
                 *
                 * We use 6:5:5 R:G:B cos that's what Xarm32VIDC wants.
                 */
#define RBITS 6
#define GBITS 5
#define BBITS 5
                vidcvideo_write(VIDC_PALREG, 0x00000000);
                for (i = 0; i < 256; i++) {
                        int r, g, b;

                        r = i & ((1 << RBITS) - 1);
                        g = (i >> (RBITS - 4)) & ((1 << GBITS) - 1);
                        b = (i >> (RBITS + GBITS - 8)) & ((1 << BBITS) - 1);
                        vidcvideo_write(VIDC_PALETTE,
                            VIDC_COL(r << (8 - RBITS) | r >> (2 * RBITS - 8),
                                g << (8 - GBITS) | g >> (2 * GBITS - 8),
                                b << (8 - BBITS) | b >> (2 * BBITS - 8)));
                }
                break;                  
        case 5: /* 32 bpp */
                vidcvideo_write(VIDC_PALREG, 0x00000000);
                for (i = 0; i < 256; i++)
                        vidcvideo_write(VIDC_PALETTE, VIDC_COL(i, i, i));  
                break;
        }
}

int
vidcvideo_blank(int video_off)
{
        int ereg;

        ereg = 1<<12;
        if (vidc_currentmode.timings.flags & VID_NHSYNC)
                ereg |= 1<<16;
        if (vidc_currentmode.timings.flags & VID_NVSYNC)
                ereg |= 1<<18;

        if (!video_off)
                vidcvideo_write(VIDC_EREG, ereg);
        else
                vidcvideo_write(VIDC_EREG, 0);
        return 0;
}

/* end of vidc20config.c */