e2022a26d0
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@11967 a1c6a512-1295-4272-9138-f99709370657
183 lines
5.9 KiB
ArmAsm
183 lines
5.9 KiB
ArmAsm
/***************************************************************************
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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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* Copyright (C) 2006 by 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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#include "config.h"
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#include "cpu.h"
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.section .icode, "ax", @progbits
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/* lcd_write_yuv420_lines()
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*
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* See http://en.wikipedia.org/wiki/YCbCr
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* ITU-R BT.601 (formerly CCIR 601):
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* |Y'| | 0.299000 0.587000 0.114000| |R|
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* |Pb| = |-0.168736 -0.331264 0.500000| |G| or 0.564334*(B - Y')
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* |Pr| | 0.500000 -0.418688 0.081312| |B| or 0.713267*(R - Y')
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* Scaled, normalized and rounded:
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* |Y'| | 65 129 25| |R| + 16 : 16->235
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* |Cb| = |-38 -74 112| |G| + 128 : 16->240
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* |Cr| |112 -94 -18| |B| + 128 : 16->240
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*
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* The inverse:
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* |R| |1.000000 0.000000 1.402000| |Y'|
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* |G| = |1.000000 -0.334136 -0.714136| |Pb|
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* |B| |1.000000 1.772000 0.000000| |Pr|
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* Scaled, normalized, rounded and tweaked to yield RGB565:
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* |R| |19611723 0 26881894| |Y' - 16| >> 27
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* |G| = |19611723 -6406711 -13692816| |Cb - 128| >> 26
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* |B| |19611723 33976259 0| |Cr - 128| >> 27
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*
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* Needs EMAC set to saturated, signed integer mode.
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*/
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.align 2
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.global lcd_write_yuv420_lines
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.type lcd_write_yuv420_lines, @function
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lcd_write_yuv420_lines:
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lea.l (-44, %sp), %sp /* free up some registers */
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movem.l %d2-%d7/%a2-%a6, (%sp)
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lea.l 0xf0000002, %a0 /* LCD data port */
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movem.l (44+4, %sp), %a1-%a4 /* Y data, Cb data, Cr data, width */
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lea.l (%a1, %a4), %a4 /* end address */
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move.l #19611723, %a5 /* y factor */
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move.l #33976259, %a6 /* bu factor */
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move.l #-6406711, %d5 /* gu factor */
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move.l #-13692816, %d6 /* gv factor */
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move.l #0x8410, %d7 /* bitmask for signed->unsigned conversion
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* of R, G and B within RGB565 at once */
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/* chroma for (very) first & second pixel */
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clr.l %d2 /* load u component */
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move.b (%a2)+, %d2
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clr.l %d3 /* load v component */
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move.b (%a3)+, %d3
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moveq.l #-128, %d0
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add.l %d0, %d2
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add.l %d0, %d3
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mac.l %a6, %d2, %acc0 /* bu */
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mac.l %d5, %d2, %acc1 /* gu */
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mac.l %d6, %d3, %acc1 /* gv */
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move.l #26881894, %d0 /* rv factor */
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mac.l %d0, %d3, %acc2 /* rv */
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/* luma for (very) first pixel */
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clr.l %d1
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move.b (%a1)+, %d1
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moveq.l #-126, %d0
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add.l %d1, %d0 /* y' (-0.5 ... +0.5) */
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mac.l %a5, %d0, %acc0
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mac.l %a5, %d0, %acc1
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mac.l %a5, %d0, %acc2
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bra.b .yuv_line_entry
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.yuv_line_loop:
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/* chroma for first & second pixel */
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clr.l %d2 /* load u component */
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move.b (%a2)+, %d2
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clr.l %d3 /* load v component */
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move.b (%a3)+, %d3
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moveq.l #-128, %d0
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add.l %d0, %d2
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add.l %d0, %d3
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mac.l %a6, %d2, %acc0 /* bu */
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mac.l %d5, %d2, %acc1 /* gu */
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mac.l %d6, %d3, %acc1 /* gv */
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move.l #26881894, %d0 /* rv factor */
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mac.l %d0, %d3, %acc2 /* rv */
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/* luma for first pixel */
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clr.l %d1
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move.b (%a1)+, %d1
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moveq.l #-126, %d0
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add.l %d1, %d0 /* y' (-0.5 ... +0.5) */
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mac.l %a5, %d0, %acc0
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mac.l %a5, %d0, %acc1
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mac.l %a5, %d0, %acc2
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move.w %d4, (%a0)
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/* LCD write is delayed one pixel to use it for filling the EMAC latency */
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/* convert to RGB565, pack and output */
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.yuv_line_entry:
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moveq.l #27, %d0
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move.l %acc0, %d2
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move.l %acc1, %d3
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move.l %acc2, %d4
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lsr.l %d0, %d2
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lsr.l %d0, %d4
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moveq.l #26, %d0
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lsr.l %d0, %d3
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lsl.l #6, %d4
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or.l %d3, %d4
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lsl.l #5, %d4
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or.l %d2, %d4
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eor.l %d7, %d4
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/* luma for second pixel as delta from the first */
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clr.l %d0
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move.b (%a1)+, %d0
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sub.l %d1, %d0
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mac.l %a5, %d0, %acc0
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mac.l %a5, %d0, %acc1
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mac.l %a5, %d0, %acc2
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move.w %d4, (%a0)
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/* LCD write is delayed one pixel to use it for filling the EMAC latency */
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/* convert to RGB565, pack and output */
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moveq.l #27, %d0
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movclr.l %acc0, %d2
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movclr.l %acc1, %d3
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movclr.l %acc2, %d4
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lsr.l %d0, %d2
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lsr.l %d0, %d4
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moveq.l #26, %d0
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lsr.l %d0, %d3
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lsl.l #6, %d4
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or.l %d3, %d4
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lsl.l #5, %d4
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or.l %d2, %d4
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eor.l %d7, %d4
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cmp.l %a1, %a4 /* run %a1 up to end of line */
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bhi.w .yuv_line_loop
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tst.l (44+4, %sp) /* use original Y pointer as a flag to */
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beq.b .yuv_exit /* distinguish between first and second */
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clr.l (44+4, %sp) /* pixel line */
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/* Rewind chroma pointers */
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movem.l (44+8, %sp), %a2-%a4 /* Cb data, Cr data, width */
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lea.l (%a1, %a4), %a4 /* end address */
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bra.w .yuv_line_loop
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.yuv_exit:
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move.w %d4, (%a0) /* write (very) last pixel */
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movem.l (%sp), %d2-%d7/%a2-%a6
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lea.l (44, %sp), %sp /* restore registers */
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rts
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.yuv_end:
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.size lcd_write_yuv420_lines, .yuv_end - lcd_write_yuv420_lines
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