135 lines
5.2 KiB
C
135 lines
5.2 KiB
C
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/***************************************************************************
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* __________ __ ___.
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* Open \______ \ ____ ____ | | _\_ |__ _______ ___
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* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
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* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
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* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
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* \/ \/ \/ \/ \/
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* $Id$
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*
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* Grayscale framework
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* gray_scroll_down() function
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*
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* This is a generic framework to use grayscale display within Rockbox
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* plugins. It obviously does not work for the player.
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*
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* Copyright (C) 2004 Jens Arnold
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*
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* All files in this archive are subject to the GNU General Public License.
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* See the file COPYING in the source tree root for full license agreement.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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****************************************************************************/
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#ifndef SIMULATOR /* not for simulator by now */
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#include "plugin.h"
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#ifdef HAVE_LCD_BITMAP /* and also not for the Player */
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#include "gray.h"
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/*---------------------------------------------------------------------------
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Scroll the whole grayscale buffer down by <count> pixels (<= 7)
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----------------------------------------------------------------------------
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black_border determines if the pixels scrolled in at the top are black
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or white
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Scrolling up/down pixel-wise is significantly slower than scrolling
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left/right or scrolling up/down byte-wise because it involves bit
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shifting. That's why it is asm optimized.
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*/
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void gray_scroll_down(int count, bool black_border)
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{
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unsigned filler;
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if ((unsigned) count > 7)
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return;
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filler = black_border ? (0xFFu << count) : 0;
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/* scroll column by column to minimize flicker */
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asm volatile (
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"mov #0,r6 \n" /* x = 0 */
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"mova .sd_shifttbl,r0 \n" /* calculate jump destination for */
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"mov.b @(r0,%6),%6 \n" /* shift amount from table */
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"bra .sd_cloop \n" /* skip table */
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"add r0,%6 \n"
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".align 2 \n"
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".sd_shifttbl: \n" /* shift jump offset table */
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".byte .sd_shift0 - .sd_shifttbl \n"
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".byte .sd_shift1 - .sd_shifttbl \n"
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".byte .sd_shift2 - .sd_shifttbl \n"
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".byte .sd_shift3 - .sd_shifttbl \n"
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".byte .sd_shift4 - .sd_shifttbl \n"
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".byte .sd_shift5 - .sd_shifttbl \n"
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".byte .sd_shift6 - .sd_shifttbl \n"
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".byte .sd_shift7 - .sd_shifttbl \n"
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".sd_cloop: \n" /* repeat for every column */
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"mov %1,r2 \n" /* get start address */
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"mov #0,r3 \n" /* current_plane = 0 */
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".sd_oloop: \n" /* repeat for every bitplane */
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"mov r2,r4 \n" /* get start address */
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"mov #0,r5 \n" /* current_row = 0 */
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"mov %5,r1 \n" /* get filler bits */
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".sd_iloop: \n" /* repeat for all rows */
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"shlr8 r1 \n" /* shift right to get residue */
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"mov.b @r4,r0 \n" /* get data byte */
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"jmp @%6 \n" /* jump into shift "path" */
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"extu.b r0,r0 \n" /* extend unsigned */
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".sd_shift6: \n" /* shift left by 0..7 bits */
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"shll2 r0 \n"
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".sd_shift4: \n"
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"shll2 r0 \n"
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".sd_shift2: \n"
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"bra .sd_shift0 \n"
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"shll2 r0 \n"
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".sd_shift7: \n"
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"shll2 r0 \n"
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".sd_shift5: \n"
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"shll2 r0 \n"
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".sd_shift3: \n"
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"shll2 r0 \n"
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".sd_shift1: \n"
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"shll r0 \n"
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".sd_shift0: \n"
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"or r0,r1 \n" /* combine with last residue */
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"mov.b r1,@r4 \n" /* store data */
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"add %2,r4 \n" /* address += width */
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"add #1,r5 \n" /* current_row++ */
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"cmp/hi r5,%3 \n" /* current_row < bheight ? */
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"bt .sd_iloop \n"
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"add %4,r2 \n" /* start_address += plane_size */
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"add #1,r3 \n" /* current_plane++ */
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"cmp/hi r3,%0 \n" /* current_plane < depth ? */
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"bt .sd_oloop \n"
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"add #1,%1 \n" /* start_address++ */
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"add #1,r6 \n" /* x++ */
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"cmp/hi r6,%2 \n" /* x < width ? */
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"bt .sd_cloop \n"
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: /* outputs */
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: /* inputs */
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/* %0 */ "r"(_graybuf->depth),
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/* %1 */ "r"(_graybuf->data),
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/* %2 */ "r"(_graybuf->width),
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/* %3 */ "r"(_graybuf->bheight),
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/* %4 */ "r"(_graybuf->plane_size),
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/* %5 */ "r"(filler),
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/* %6 */ "r"(count)
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: /* clobbers */
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"r0", "r1", "r2", "r3", "r4", "r5", "r6"
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);
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}
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#endif // #ifdef HAVE_LCD_BITMAP
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#endif // #ifndef SIMULATOR
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