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/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Copyright (C) 2006 by Jens Arnold
*
* 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; either version 2
* of the License, or (at your option) any later version.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/
#include "config.h"
#include "cpu.h"
.section .icode, "ax", @progbits
/* lcd_write_yuv420_lines()
*
* See http://en.wikipedia.org/wiki/YCbCr
* ITU-R BT.601 (formerly CCIR 601):
* |Y'| | 0.299000 0.587000 0.114000| |R|
* |Pb| = |-0.168736 -0.331264 0.500000| |G| or 0.564334*(B - Y')
* |Pr| | 0.500000 -0.418688 0.081312| |B| or 0.713267*(R - Y')
* Scaled, normalized and rounded:
* |Y'| | 65 129 25| |R| + 16 : 16->235
* |Cb| = |-38 -74 112| |G| + 128 : 16->240
* |Cr| |112 -94 -18| |B| + 128 : 16->240
*
* The inverse:
* |R| |1.000000 0.000000 1.402000| |Y'|
* |G| = |1.000000 -0.334136 -0.714136| |Pb|
* |B| |1.000000 1.772000 0.000000| |Pr|
* Scaled, normalized, rounded and tweaked to yield RGB565:
* |R| |19611723 0 26881894| |Y' - 16| >> 27
* |G| = |19611723 -6406711 -13692816| |Cb - 128| >> 26
* |B| |19611723 33976259 0| |Cr - 128| >> 27
*
* Needs EMAC set to saturated, signed integer mode.
*
* register usage:
* %a0 - LCD data port
* %a1 - Y pointer
* %a2 - C pointer
* %a3 - C width
* %a4 - Y end address
* %a5 - Y factor
* %a6 - BU factor
* %d0 - scratch
* %d1 - B, previous Y \ alternating
* %d2 - U / B, previous Y /
* %d3 - V / G
* %d4 - R / output pixel
* %d5 - GU factor
* %d6 - GV factor
* %d7 - RGB signed -> unsigned conversion mask
*/
.align 2
.global lcd_write_yuv420_lines
.type lcd_write_yuv420_lines, @function
lcd_write_yuv420_lines:
lea.l (-44, %sp), %sp /* free up some registers */
movem.l %d2-%d7/%a2-%a6, (%sp)
lea.l 0xf0000002, %a0 /* LCD data port */
movem.l (44+4, %sp), %a1-%a3 /* Y data, C data, C width */
lea.l (%a1, %a3*2), %a4 /* Y end address */
move.l #19611723, %a5 /* y factor */
move.l #33976259, %a6 /* bu factor */
move.l #-6406711, %d5 /* gu factor */
move.l #-13692816, %d6 /* gv factor */
move.l #0x8410, %d7 /* bitmask for signed->unsigned conversion
* of R, G and B within RGB565 at once */
/* chroma for first 2x2 pixel block */
clr.l %d3 /* load v component */
move.b (%a2, %a3), %d3
clr.l %d2 /* load u component */
move.b (%a2)+, %d2
moveq.l #-128, %d0
add.l %d0, %d2
add.l %d0, %d3
mac.l %a6, %d2, %acc0 /* bu */
mac.l %d5, %d2, %acc1 /* gu */
mac.l %d6, %d3, %acc1 /* gv */
move.l #26881894, %d0 /* rv factor */
mac.l %d0, %d3, %acc2 /* rv */
/* luma for very first pixel (top left) */
clr.l %d1
move.b (%a1, %a3*2), %d1
moveq.l #-126, %d0
add.l %d1, %d0 /* y' (-0.5 ... +0.5) */
mac.l %a5, %d0, %acc0
mac.l %a5, %d0, %acc1
mac.l %a5, %d0, %acc2
bra.b .yuv_line_entry
.yuv_line_loop:
/* chroma for 2x2 pixel block */
clr.l %d3 /* load v component */
move.b (%a2, %a3), %d3
clr.l %d2 /* load u component */
move.b (%a2)+, %d2
moveq.l #-128, %d0
add.l %d0, %d2
add.l %d0, %d3
mac.l %a6, %d2, %acc0 /* bu */
mac.l %d5, %d2, %acc1 /* gu */
mac.l %d6, %d3, %acc1 /* gv */
move.l #26881894, %d0 /* rv factor */
mac.l %d0, %d3, %acc2 /* rv */
/* luma for first pixel (top left) */
clr.l %d1
move.b (%a1, %a3*2), %d1
moveq.l #-126, %d0
add.l %d1, %d0 /* y' (-0.5 ... +0.5) */
mac.l %a5, %d0, %acc0
mac.l %a5, %d0, %acc1
mac.l %a5, %d0, %acc2
move.w %d4, (%a0)
/* LCD write is delayed one pixel to use it for filling the EMAC latency */
/* convert to RGB565, pack and output */
.yuv_line_entry:
moveq.l #27, %d0
move.l %acc0, %d2
move.l %acc1, %d3
move.l %acc2, %d4
lsr.l %d0, %d2
lsr.l %d0, %d4
moveq.l #26, %d0
lsr.l %d0, %d3
lsl.l #6, %d4
or.l %d3, %d4
lsl.l #5, %d4
or.l %d2, %d4
eor.l %d7, %d4
/* luma for second pixel (bottom left) as delta from the first */
clr.l %d2
move.b (%a1)+, %d2
move.l %d2, %d0
sub.l %d1, %d0
mac.l %a5, %d0, %acc0
mac.l %a5, %d0, %acc1
mac.l %a5, %d0, %acc2
move.w %d4, (%a0)
/* LCD write is delayed one pixel to use it for filling the EMAC latency */
/* convert to RGB565, pack and output */
moveq.l #27, %d0
move.l %acc0, %d1
move.l %acc1, %d3
move.l %acc2, %d4
lsr.l %d0, %d1
lsr.l %d0, %d4
moveq.l #26, %d0
lsr.l %d0, %d3
lsl.l #6, %d4
or.l %d3, %d4
lsl.l #5, %d4
or.l %d1, %d4
eor.l %d7, %d4
/* luma for third pixel (top right) as delta from the second */
clr.l %d1
move.b (%a1, %a3*2), %d1
move.l %d1, %d0
sub.l %d2, %d0
mac.l %a5, %d0, %acc0
mac.l %a5, %d0, %acc1
mac.l %a5, %d0, %acc2
move.w %d4, (%a0)
/* LCD write is delayed one pixel to use it for filling the EMAC latency */
/* convert to RGB565, pack and output */
moveq.l #27, %d0
move.l %acc0, %d2
move.l %acc1, %d3
move.l %acc2, %d4
lsr.l %d0, %d2
lsr.l %d0, %d4
moveq.l #26, %d0
lsr.l %d0, %d3
lsl.l #6, %d4
or.l %d3, %d4
lsl.l #5, %d4
or.l %d2, %d4
eor.l %d7, %d4
/* luma for fourth pixel (bottom right) as delta from the third */
clr.l %d2
move.b (%a1)+, %d2
move.l %d2, %d0
sub.l %d1, %d0
mac.l %a5, %d0, %acc0
mac.l %a5, %d0, %acc1
mac.l %a5, %d0, %acc2
move.w %d4, (%a0)
/* LCD write is delayed one pixel to use it for filling the EMAC latency */
/* convert to RGB565, pack and output */
moveq.l #27, %d0
movclr.l %acc0, %d1
movclr.l %acc1, %d3
movclr.l %acc2, %d4
lsr.l %d0, %d1
lsr.l %d0, %d4
moveq.l #26, %d0
lsr.l %d0, %d3
lsl.l #6, %d4
or.l %d3, %d4
lsl.l #5, %d4
or.l %d1, %d4
eor.l %d7, %d4
cmp.l %a1, %a4 /* run %a1 up to end of line */
bhi.w .yuv_line_loop
move.w %d4, (%a0) /* write (very) last pixel */
movem.l (%sp), %d2-%d7/%a2-%a6
lea.l (44, %sp), %sp /* restore registers */
rts
.yuv_end:
.size lcd_write_yuv420_lines, .yuv_end - lcd_write_yuv420_lines
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