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/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Copyright (C) 2007 by Andree Buschmann
*
* All files in this archive are subject to the GNU General Public License.
* See the file COPYING in the source tree root for full license agreement.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/
/****************************************************************************
* void lcd_write_yuv_420_lines(unsigned char const * const src[3],
* int width,
* int stride);
*
* |R| |1.000000 -0.000001 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 RGB 565:
* |R| |74 0 101| |Y' - 16| >> 9
* |G| = |74 -24 -51| |Cb - 128| >> 8
* |B| |74 128 0| |Cr - 128| >> 9
*/
.section .icode, "ax", %progbits
.align 2
.global lcd_write_yuv420_lines
.type lcd_write_yuv420_lines, %function
lcd_write_yuv420_lines:
/* r0 = yuv_src */
/* r1 = width */
/* r2 = stride */
stmfd sp!, { r4-r12 } /* save non-scratch */
ldmia r0, { r10, r11, r12 } /* r10 = yuv_src[0] = Y'_p */
/* r11 = yuv_src[1] = Cb_p */
/* r12 = yuv_src[2] = Cr_p */
add r2, r10, r2 /* r2 = &ysrc[stride] */
add r3, r1, r1, asl #1 /* number of bytes for chroma buffer */
add r3, r3, #15 /* plus room for 3 additional words, */
bic r3, r3, #3 /* rounded up to multiples of 4 byte */
sub sp, sp, r3 /* and allocate on stack */
stmia sp, {r1, r2, r3} /* width, &ysrc[stride], stack_alloc */
mov r7, r1 /* r7 = loop count */
add r8, sp, #12 /* chroma buffer */
mov r9, #0x30000000 /* LCD data port */
/* 1st loop start */
10: /* loop start */
ldrb r0, [r11], #1 /* r0 = *usrc++ = *Cb_p++ */
ldrb r1, [r12], #1 /* r1 = *vsrc++ = *Cr_p++ */
sub r0, r0, #128 /* r0 = Cb-128 */
sub r1, r1, #128 /* r1 = Cr-128 */
add r3, r1, r1, asl #1 /* r3 = Cr*51 + Cb*24 */
add r3, r3, r3, asl #4
add r3, r3, r0, asl #3
add r3, r3, r0, asl #4
add r4, r1, r1, asl #2 /* r1 = Cr*101 */
add r4, r4, r1, asl #5
add r1, r4, r1, asl #6
add r1, r1, #256 /* r1 = rv = (r1 + 256) >> 9 */
mov r1, r1, asr #9
strb r1, [r8], #1 /* store r1 to chroma_buf */
rsb r3, r3, #128 /* r3 = guv = (-r3 + 128) >> 8 */
mov r3, r3, asr #8
strb r3, [r8], #1 /* store r3 to chroma_buf */
add r0, r0, #2 /* r0 = bu = (Cb*128 + 256) >> 9 */
mov r0, r0, asr #2
strb r0, [r8], #1 /* store r0 to chroma_buf */
/* 1st loop, first pixel */
ldrb r5, [r10], #1 /* r5 = *ysrc++ = *Y'_p++ */
sub r5, r5, #16 /* r5 = (Y'-16) * 74 */
add r2, r5, r5, asl #2
add r5, r2, r5, asl #5
add r6, r1, r5, asr #8 /* r6 = r = (Y >> 9) + rv */
add r2, r3, r5, asr #7 /* r2 = g = (Y >> 8) + guv */
add r4, r0, r5, asr #8 /* r4 = b = (Y >> 9) + bu */
orr r5, r6, r4 /* check if clamping is needed... */
orr r5, r5, r2, asr #1 /* ...at all */
cmp r5, #31
bls 15f /* -> no clamp */
cmp r6, #31 /* clamp r */
mvnhi r6, r6, asr #31
andhi r6, r6, #31
cmp r2, #63 /* clamp g */
mvnhi r2, r2, asr #31
andhi r2, r2, #63
cmp r4, #31 /* clamp b */
mvnhi r4, r4, asr #31
andhi r4, r4, #31
15: /* no clamp */
orr r4, r4, r2, lsl #5 /* pixel = r<<11 | g<<5 | b */
orr r4, r4, r6, lsl #11
strh r4, [r9] /* write pixel */
/* 1st loop, second pixel */
ldrb r5, [r10], #1 /* r5 = *ysrc++ = *Y'_p++ */
sub r5, r5, #16 /* r5 = (Y'-16) * 74 */
add r2, r5, r5, asl #2
add r5, r2, r5, asl #5
add r6, r1, r5, asr #8 /* r6 = r = (Y >> 9) + rv */
add r2, r3, r5, asr #7 /* r2 = g = (Y >> 8) + guv */
add r4, r0, r5, asr #8 /* r4 = b = (Y >> 9) + bu */
orr r5, r6, r4 /* check if clamping is needed... */
orr r5, r5, r2, asr #1 /* ...at all */
cmp r5, #31
bls 15f /* -> no clamp */
cmp r6, #31 /* clamp r */
mvnhi r6, r6, asr #31
andhi r6, r6, #31
cmp r2, #63 /* clamp g */
mvnhi r2, r2, asr #31
andhi r2, r2, #63
cmp r4, #31 /* clamp b */
mvnhi r4, r4, asr #31
andhi r4, r4, #31
15: /* no clamp */
orr r4, r4, r2, lsl #5 /* pixel = r<<11 | g<<5 | b */
orr r4, r4, r6, lsl #11
strh r4, [r9] /* write pixel */
subs r7, r7, #2 /* check for loop end */
bgt 10b /* back to beginning */
/* 1st loop end */
add r8, sp, #12 /* chroma buffer */
ldmia sp, { r7, r10 } /* r7 = loop count */
/* r10 = &ysrc[stride] */
/* 2nd loop start */
20: /* loop start */
/* restore r1, r3 and r0 from chroma buffer */
ldrsb r1, [r8], #1
ldrsb r3, [r8], #1
ldrsb r0, [r8], #1
/* 2nd loop, first pixel */
ldrb r5, [r10], #1 /* r5 = *ysrc++ = *Y'_p++ */
sub r5, r5, #16 /* r5 = (Y'-16) * 74 */
add r2, r5, r5, asl #2
add r5, r2, r5, asl #5
add r6, r1, r5, asr #8 /* r6 = r = (Y >> 9) + rv */
add r2, r3, r5, asr #7 /* r2 = g = (Y >> 8) + guv */
add r4, r0, r5, asr #8 /* r4 = b = (Y >> 9) + bu */
orr r5, r6, r4 /* check if clamping is needed... */
orr r5, r5, r2, asr #1 /* ...at all */
cmp r5, #31
bls 15f /* -> no clamp */
cmp r6, #31 /* clamp r */
mvnhi r6, r6, asr #31
andhi r6, r6, #31
cmp r2, #63 /* clamp g */
mvnhi r2, r2, asr #31
andhi r2, r2, #63
cmp r4, #31 /* clamp b */
mvnhi r4, r4, asr #31
andhi r4, r4, #31
15: /* no clamp */
orr r4, r4, r2, lsl #5 /* pixel = r<<11 | g<<5 | b */
orr r4, r4, r6, lsl #11
strh r4, [r9] /* write pixel */
/* 2nd loop, second pixel */
ldrb r5, [r10], #1 /* r5 = *ysrc++ = *Y'_p++ */
sub r5, r5, #16 /* r5 = (Y'-16) * 74 */
add r2, r5, r5, asl #2
add r5, r2, r5, asl #5
add r6, r1, r5, asr #8 /* r6 = r = (Y >> 9) + rv */
add r2, r3, r5, asr #7 /* r2 = g = (Y >> 8) + guv */
add r4, r0, r5, asr #8 /* r4 = b = (Y >> 9) + bu */
orr r5, r6, r4 /* check if clamping is needed... */
orr r5, r5, r2, asr #1 /* ...at all */
cmp r5, #31
bls 15f /* -> no clamp */
cmp r6, #31 /* clamp r */
mvnhi r6, r6, asr #31
andhi r6, r6, #31
cmp r2, #63 /* clamp g */
mvnhi r2, r2, asr #31
andhi r2, r2, #63
cmp r4, #31 /* clamp b */
mvnhi r4, r4, asr #31
andhi r4, r4, #31
15: /* no clamp */
orr r4, r4, r2, lsl #5 /* pixel = r<<11 | g<<5 | b */
orr r4, r4, r6, lsl #11
strh r4, [r9] /* write pixel */
subs r7, r7, #2 /* check for loop end */
bgt 20b /* back to beginning */
/* 2nd loop end */
ldr r3, [sp, #8]
add sp, sp, r3 /* deallocate buffer */
ldmfd sp!, { r4-r12 } /* restore registers */
bx lr
.ltorg
.size lcd_write_yuv420_lines, .-lcd_write_yuv420_lines
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