/*************************************************************************** * __________ __ ___. * Open \______ \ ____ ____ | | _\_ |__ _______ ___ * Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ / * Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < < * Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \ * \/ \/ \/ \/ \/ * * 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