Implement a C version lcd-as-memframe.c and move it and the asm to firmware/asm.

Change-Id: I20c3af0368202493d54fb776530300a39d47873a

3 files changed, 880 insertions, 0 deletions

diff --git a/firmware/asm/SOURCES b/firmware/asm/SOURCES
index 805727ea93..216089f003 100644
--- a/firmware/asm/SOURCES
+++ b/firmware/asm/SOURCES
@@ -5,3 +5,10 @@ memmove.c
 memset.c
 strlen.c
 #endif
+
+#if (defined(SANSA_E200) || defined(GIGABEAT_F) || defined(GIGABEAT_S) || \
+    defined(CREATIVE_ZVx) || defined(SANSA_CONNECT) || defined(SANSA_FUZEPLUS) || \
+    defined(COWON_D2) || defined(MINI2440) || (defined(MROBE_500) && !defined(LCD_USE_DMA))) && \
+    !defined(SIMULATOR)
+lcd-as-memframe.c
+#endif
diff --git a/firmware/asm/arm/lcd-as-memframe.S b/firmware/asm/arm/lcd-as-memframe.S
new file mode 100644
index 0000000000..52ab0447c2
--- /dev/null
+++ b/firmware/asm/arm/lcd-as-memframe.S
@@ -0,0 +1,692 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Copyright (C) 2007 by Michael Sevakis
+ *
+ * ARM code for memory framebuffer LCDs
+ *
+ * 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"
+
+/****************************************************************************
+ * void lcd_copy_buffer_rect(fb_data *dst, fb_data *src, int width,
+ *                           int height);
+ */
+     .section    .icode.lcd_copy_buffer_rect, "ax", %progbits
+     .align      2
+     .global     lcd_copy_buffer_rect
+     .type       lcd_copy_buffer_rect, %function
+                                        @ r0 = dst
+                                        @ r1 = src
+                                        @ r2 = width
+                                        @ r3 = height
+lcd_copy_buffer_rect:                   @
+    stmfd   sp!, { r4-r11, lr }         @ save non-scratch regs
+    mov     r5, r2                      @ r5 = cached width
+    rsb     r4, r2, #LCD_WIDTH          @ r4 = LCD_WIDTH - width
+10: @ copy line                         @
+    subs    r2, r5, #1                  @ r2 = width - 1
+    beq     40f @ finish line           @ one halfword? skip to trailing copy
+    tst     r0, #2                      @ word aligned?
+    beq     20f @ rem copy              @ yes? skip to word copy
+    ldrh    r6, [r1], #2                @ copy leading halfword
+    subs    r2, r2, #1                  @
+    strh    r6, [r0], #2                @
+    ble     40f @ finish line           @ next line if lt or finish
+                                        @ trailing halfword if eq
+20: @ rem copy                          @
+    sub     r14, r2, #1                 @ wrap remaining width mod 16 after word
+                                        @ align (rw)
+    and     r14, r14, #0xe              @ r14 = 14, 0, 2, 4, 6, 8, 10, 12
+    add     pc, pc, r14, lsl #3         @ branch to 32-byte align
+    nop                                 @
+    ldr     r6, [r1], #4                @ rw % 16 = 2 or 3 (0)
+    subs    r2, r2, #2                  @
+    str     r6, [r0], #4                @
+    b       25f @ copy up done          @
+    ldmia   r1!, { r6-r7 }              @ rw % 16 = 4 or 5 (2)
+    subs    r2, r2, #4                  @
+    stmia   r0!, { r6-r7 }              @
+    b       25f @ copy up done          @
+    ldmia   r1!, { r6-r8 }              @ rw % 16 = 6 or 7 (4)
+    subs    r2, r2, #6                  @
+    stmia   r0!, { r6-r8 }              @
+    b       25f @ copy up done          @
+    ldmia   r1!, { r6-r9 }              @ rw % 16 = 8 or 9 (6)
+    subs    r2, r2, #8                  @
+    stmia   r0!, { r6-r9 }              @
+    b       25f @ copy up done          @
+    ldmia   r1!, { r6-r10 }             @ rw % 16 = 10 or 11 (8)
+    subs    r2, r2, #10                 @
+    stmia   r0!, { r6-r10 }             @
+    b       25f @ copy up done          @
+    ldmia   r1!, { r6-r11 }             @ rw % 16 = 12 or 13 (10)
+    subs    r2, r2, #12                 @
+    stmia   r0!, { r6-r11 }             @
+    b       25f @ copy up done          @
+    ldmia   r1!, { r6-r12 }             @ rw % 16 = 14 or 15 (12)
+    subs    r2, r2, #14                 @
+    stmia   r0!, { r6-r12 }             @
+25: @ copy up done                      @
+    ble     40f @ finish line           @
+30: @ octword loop                      @ rw % 16 = 0 or 1 (14)
+    ldmia   r1!, { r6-r12, r14 }        @ copy 16 pixels per loop
+    subs    r2, r2, #16                 @
+    stmia   r0!, { r6-r12, r14 }        @
+    bgt     30b @ octword loop          @
+40: @ finish line                       @
+    ldreqh  r6, [r1], #2                @ finish last halfword if eq ...
+    add     r1, r1, r4, lsl #1          @
+    streqh  r6, [r0], #2                @ ...
+    add     r0, r0, r4, lsl #1          @
+    subs    r3, r3, #1                  @ next line
+    bgt     10b @ copy line             @
+    ldmpc   regs=r4-r11                 @ restore regs and return
+    .size   lcd_copy_buffer_rect, .-lcd_copy_buffer_rect
+
+
+/****************************************************************************
+ * void lcd_write_yuv420_lines(fb_data *dst,
+ *                              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
+ *
+ * Write four RGB565 pixels in the following order on each loop:
+ * 1 3 + > down
+ * 2 4 \/ left
+ */
+    .section    .icode.lcd_write_yuv420_lines, "ax", %progbits
+    .align      2
+    .global     lcd_write_yuv420_lines
+    .type       lcd_write_yuv420_lines, %function
+lcd_write_yuv420_lines:
+                                        @ r0 = dst
+                                        @ r1 = yuv_src
+                                        @ r2 = width
+                                        @ r3 = stride
+    stmfd       sp!, { r4-r10, lr }     @ save non-scratch
+    ldmia       r1, { r4, r5, r6 }      @ r4 = yuv_src[0] = Y'_p
+                                        @ r5 = yuv_src[1] = Cb_p
+                                        @ r6 = yuv_src[2] = Cr_p
+                                        @ r1 = scratch
+    sub         r3, r3, #1              @
+10: @ loop line                         @
+    ldrb        r7, [r4], #1            @ r7 = *Y'_p++;
+    ldrb        r8, [r5], #1            @ r8 = *Cb_p++;
+    ldrb        r9, [r6], #1            @ r9 = *Cr_p++;
+                                        @
+    sub         r7, r7, #16             @ r7 = Y = (Y' - 16)*74
+    add         r12, r7, r7, asl #2     @ actually (Y' - 16)*37 and shift right
+    add         r7, r12, r7, asl #5     @ by one less when adding - same for all
+                                        @
+    sub         r8, r8, #128            @ Cb -= 128
+    sub         r9, r9, #128            @ Cr -= 128
+                                        @
+    add         r10, r9, r9, asl #1     @ r10 = Cr*51 + Cb*24
+    add         r10, r10, r10, asl #4   @
+    add         r10, r10, r8, asl #3    @
+    add         r10, r10, r8, asl #4    @
+                                        @
+    add         lr, r9, r9, asl #2      @ r9 = Cr*101
+    add         lr, lr, r9, asl #5      @
+    add         r9, lr, r9, asl #6      @
+                                        @
+    add         r8, r8, #2              @ r8 = bu = (Cb*128 + 128) >> 8
+    mov         r8, r8, asr #2          @
+    add         r9, r9, #256            @ r9 = rv = (r9 + 256) >> 9
+    mov         r9, r9, asr #9          @
+    rsb         r10, r10, #128          @ r10 = guv = (-r10 + 128) >> 8
+    mov         r10, r10, asr #8        @
+                                        @ compute R, G, and B
+    add         r1, r8, r7, asr #8      @ r1  = b = (Y >> 9) + bu
+    add         lr, r9, r7, asr #8      @ lr = r = (Y >> 9) + rv
+    add         r7, r10, r7, asr #7     @ r7  = g = (Y >> 8) + guv
+                                        @
+#if ARM_ARCH >= 6
+    usat        r1, #5, r1              @ clamp b
+    usat        lr, #5, lr              @ clamp r
+    usat        r7, #6, r7              @ clamp g
+#else
+    orr         r12, r1, lr             @ check if clamping is needed...
+    orr         r12, r12, r7, asr #1    @ ...at all
+    cmp         r12, #31                @
+    bls         15f @ no clamp          @
+    cmp         r1, #31                 @ clamp b
+    mvnhi       r1, r1, asr #31         @
+    andhi       r1, r1, #31             @
+    cmp         lr, #31                 @ clamp r
+    mvnhi       lr, lr, asr #31         @
+    andhi       lr, lr, #31             @
+    cmp         r7, #63                 @ clamp g
+    mvnhi       r7, r7, asr #31         @
+    andhi       r7, r7, #63             @
+15: @ no clamp                          @
+#endif
+                                        @
+    ldrb        r12, [r4, r3]           @ r12 = Y' = *(Y'_p + stride)
+                                        @
+    orr         r1, r1, r7, lsl #5      @ r4 |= (g << 5)
+    orr         r1, r1, lr, lsl #11     @ r4 = b | (r << 11)
+
+#if LCD_WIDTH >= LCD_HEIGHT
+    strh        r1, [r0]                @
+#elif LCD_WIDTH < 256
+    strh        r1, [r0], #LCD_WIDTH    @ store pixel
+#else
+    strh        r1, [r0]                @
+#endif
+                                        @
+    sub         r7, r12, #16            @ r7 = Y = (Y' - 16)*74
+    add         r12, r7, r7, asl #2     @
+    add         r7, r12, r7, asl #5     @
+                                        @ compute R, G, and B
+    add         r1, r8, r7, asr #8      @ r1  = b = (Y >> 9) + bu
+    add         lr, r9, r7, asr #8      @ lr = r = (Y >> 9) + rv
+    add         r7, r10, r7, asr #7     @ r7  = g = (Y >> 8) + guv
+                                        @
+#if ARM_ARCH >= 6
+    usat        r1, #5, r1              @ clamp b
+    usat        lr, #5, lr              @ clamp r
+    usat        r7, #6, r7              @ clamp g
+#else
+    orr         r12, r1, lr             @ check if clamping is needed...
+    orr         r12, r12, r7, asr #1    @ ...at all
+    cmp         r12, #31                @
+    bls         15f @ no clamp          @
+    cmp         r1, #31                 @ clamp b
+    mvnhi       r1, r1, asr #31         @
+    andhi       r1, r1, #31             @
+    cmp         lr, #31                 @ clamp r
+    mvnhi       lr, lr, asr #31         @
+    andhi       lr, lr, #31             @
+    cmp         r7, #63                 @ clamp g
+    mvnhi       r7, r7, asr #31         @
+    andhi       r7, r7, #63             @
+15: @ no clamp                          @
+#endif
+                                        @
+    ldrb        r12, [r4], #1           @ r12 = Y' = *(Y'_p++)
+                                        @
+    orr         r1, r1, lr, lsl #11     @ r1 = b | (r << 11)
+    orr         r1, r1, r7, lsl #5      @ r1 |= (g << 5)
+
+#if LCD_WIDTH >= LCD_HEIGHT
+    add         r0, r0, #2*LCD_WIDTH    @
+    strh        r1, [r0]        @ store pixel
+    sub         r0, r0, #2*LCD_WIDTH    @
+#elif LCD_WIDTH < 256
+    strh        r1, [r0, #-LCD_WIDTH-2] @ store pixel
+#else
+    strh        r1, [r0, #-2]           @
+    add         r0, r0, #LCD_WIDTH      @
+#endif
+                                        @
+    sub         r7, r12, #16            @ r7 = Y = (Y' - 16)*74
+    add         r12, r7, r7, asl #2     @
+    add         r7, r12, r7, asl #5     @
+                                        @ compute R, G, and B
+    add         r1, r8, r7, asr #8      @ r1  = b = (Y >> 9) + bu
+    add         lr, r9, r7, asr #8      @ lr = r = (Y >> 9) + rv
+    add         r7, r10, r7, asr #7     @ r7  = g = (Y >> 8) + guv
+                                        @
+#if ARM_ARCH >= 6
+    usat        r1, #5, r1              @ clamp b
+    usat        lr, #5, lr              @ clamp r
+    usat        r7, #6, r7              @ clamp g
+#else
+    orr         r12, r1, lr             @ check if clamping is needed...
+    orr         r12, r12, r7, asr #1    @ ...at all
+    cmp         r12, #31                @
+    bls         15f @ no clamp          @
+    cmp         r1, #31                 @ clamp b
+    mvnhi       r1, r1, asr #31         @
+    andhi       r1, r1, #31             @
+    cmp         lr, #31                 @ clamp r
+    mvnhi       lr, lr, asr #31         @
+    andhi       lr, lr, #31             @
+    cmp         r7, #63                 @ clamp g
+    mvnhi       r7, r7, asr #31         @
+    andhi       r7, r7, #63             @
+15: @ no clamp                          @
+#endif
+                                        @
+    ldrb        r12, [r4, r3]           @ r12 = Y' = *(Y'_p + stride)
+                                        @
+    orr         r1, r1, r7, lsl #5      @ r1 = b | (g << 5)
+    orr         r1, r1, lr, lsl #11     @ r1 |= (r << 11)
+
+#if LCD_WIDTH >= LCD_HEIGHT
+    strh        r1, [r0, #2]
+#elif LCD_WIDTH <  256
+    strh        r1, [r0, #LCD_WIDTH]!   @ store pixel
+#else
+    strh        r1, [r0]                @
+#endif
+                                        @
+    sub         r7, r12, #16            @ r7 = Y = (Y' - 16)*74
+    add         r12, r7, r7, asl #2     @
+    add         r7, r12, r7, asl #5     @
+                                        @ compute R, G, and B
+    add         r1, r8, r7, asr #8      @ r1  = b = (Y >> 9) + bu
+    add         lr, r9, r7, asr #8      @ lr = r = (Y >> 9) + rv
+    add         r7, r10, r7, asr #7     @ r7  = g = (Y >> 8) + guv
+                                        @
+#if ARM_ARCH >= 6
+    usat        r1, #5, r1              @ clamp b
+    usat        lr, #5, lr              @ clamp r
+    usat        r7, #6, r7              @ clamp g
+#else
+    orr         r12, r1, lr             @ check if clamping is needed...
+    orr         r12, r12, r7, asr #1    @ ...at all
+    cmp         r12, #31                @
+    bls         15f @ no clamp          @
+    cmp         r1, #31                 @ clamp b
+    mvnhi       r1, r1, asr #31         @
+    andhi       r1, r1, #31             @
+    cmp         lr, #31                 @ clamp r
+    mvnhi       lr, lr, asr #31         @
+    andhi       lr, lr, #31             @
+    cmp         r7, #63                 @ clamp g
+    mvnhi       r7, r7, asr #31         @
+    andhi       r7, r7, #63             @
+15: @ no clamp                          @
+#endif
+                                        @
+    orr         r12, r1, lr, lsl #11    @ r12 = b | (r << 11)
+    orr         r12, r12, r7, lsl #5    @ r12 |= (g << 5)
+
+#if LCD_WIDTH >= LCD_HEIGHT
+    add         r0, r0, #2*LCD_WIDTH
+    strh        r12, [r0, #2]
+#if LCD_WIDTH <= 512
+    sub         r0, r0, #(2*LCD_WIDTH)-4
+#else
+    sub         r0, r0, #(2*LCD_WIDTH)
+    add         r0, r0, #4
+#endif
+#else
+    strh        r12, [r0, #-2]          @ store pixel
+#if LCD_WIDTH < 256
+    add         r0, r0, #2*LCD_WIDTH    @
+#else
+    add         r0, r0, #LCD_WIDTH      @
+#endif
+#endif
+                                        @
+    subs        r2, r2, #2              @ subtract block from width
+    bgt         10b @ loop line         @
+                                        @
+    ldmpc       regs=r4-r10             @ restore registers and return
+    .ltorg                              @ dump constant pool
+    .size   lcd_write_yuv420_lines, .-lcd_write_yuv420_lines
+
+
+/****************************************************************************
+ * void lcd_write_yuv420_lines_odither(fb_data *dst,
+ *                                      unsigned char const * const src[3],
+ *                                      int width,
+ *                                      int stride,
+ *                                      int x_screen,
+ *                                      int y_screen);
+ *
+ *   |R|   |1.000000 -0.000001  1.402000| |Y'|
+ *   |G| = |1.000000 -0.334136 -0.714136| |Pb|
+ *   |B|   |1.000000  1.772000  0.000000| |Pr|
+ *   Red scaled at twice g & b but at same precision to place it in correct
+ *   bit position after multiply and leave instruction count lower.
+ *   |R|   |258   0  408| |Y' -  16|
+ *   |G| = |149 -49 -104| |Cb - 128|
+ *   |B|   |149 258    0| |Cr - 128|
+ *
+ * Write four RGB565 pixels in the following order on each loop:
+ * 1 3 + > down
+ * 2 4 \/ left
+ *
+ * Kernel pattern (raw|rotated|use order):
+ * 5 3 4 2   2 6 3 7     row0   row2          > down
+ * 1 7 0 6 | 4 0 5 1 | 2 4 6 0 3 5 7 1 col0     left
+ * 4 2 5 3 | 3 7 2 6 | 3 5 7 1 2 4 6 0 col2  \/
+ * 0 6 1 7   5 1 4 0
+ */
+    .section    .icode.lcd_write_yuv420_lines_odither, "ax", %progbits
+    .align      2
+    .global     lcd_write_yuv420_lines_odither
+    .type       lcd_write_yuv420_lines_odither, %function
+lcd_write_yuv420_lines_odither:
+                                        @ r0 = dst
+                                        @ r1 = yuv_src
+                                        @ r2 = width
+                                        @ r3 = stride
+                                        @ [sp]   = x_screen
+                                        @ [sp+4] = y_screen
+    stmfd       sp!, { r4-r11, lr }     @ save non-scratch
+    ldmia       r1, { r4, r5, r6 }      @ r4 = yuv_src[0] = Y'_p
+                                        @ r5 = yuv_src[1] = Cb_p
+                                        @ r6 = yuv_src[2] = Cr_p
+                                        @
+    sub         r3, r3, #1              @
+    add         r1, sp, #36             @ Line up pattern and kernel quadrant
+    ldmia       r1, { r12, r14 }        @
+    eor         r14, r14, r12           @
+    and         r14, r14, #0x2          @
+    mov         r14, r14, lsl #6        @ 0x00 or 0x80
+10: @ loop line                         @
+                                        @
+    ldrb        r7, [r4], #1            @ r7 = *Y'_p++;
+    ldrb        r8, [r5], #1            @ r8 = *Cb_p++;
+    ldrb        r9, [r6], #1            @ r9 = *Cr_p++;
+                                        @
+    eor         r14, r14, #0x80         @ flip pattern quadrant
+                                        @
+    sub         r7, r7, #16             @ r7 = Y = (Y' - 16)*149
+    add         r12, r7, r7, asl #2     @
+    add         r12, r12, r12, asl #4   @
+    add         r7, r12, r7, asl #6     @
+                                        @
+    sub         r8, r8, #128            @ Cb -= 128
+    sub         r9, r9, #128            @ Cr -= 128
+                                        @
+    add         r10, r8, r8, asl #4     @ r10 = guv = Cr*104 + Cb*49
+    add         r10, r10, r8, asl #5    @
+    add         r10, r10, r9, asl #3    @
+    add         r10, r10, r9, asl #5    @
+    add         r10, r10, r9, asl #6    @
+                                        @
+    mov         r8, r8, asl #1          @ r8 = bu = Cb*258
+    add         r8, r8, r8, asl #7      @
+                                        @
+    add         r9, r9, r9, asl #1      @ r9 = rv = Cr*408
+    add         r9, r9, r9, asl #4      @
+    mov         r9, r9, asl #3          @
+                                        @
+                                        @ compute R, G, and B
+    add         r1, r8, r7              @ r1  = b' = Y + bu
+    add         r11, r9, r7, asl #1     @ r11 = r' = Y*2 + rv
+    rsb         r7, r10, r7             @ r7  = g' = Y + guv
+                                        @
+                                        @ r8 = bu, r9 = rv, r10 = guv
+                                        @
+    sub         r12, r1, r1, lsr #5     @ r1 = 31/32*b + b/256
+    add         r1, r12, r1, lsr #8     @
+                                        @
+    sub         r12, r11, r11, lsr #5   @ r11 = 31/32*r + r/256
+    add         r11, r12, r11, lsr #8   @
+                                        @
+    sub         r12, r7, r7, lsr #6     @ r7 = 63/64*g + g/256
+    add         r7, r12, r7, lsr #8     @
+                                        @
+    add         r12, r14, #0x100        @
+                                        @
+    add         r1, r1, r12             @ b = r1 + delta
+    add         r11, r11, r12, lsl #1   @ r = r11 + delta*2
+    add         r7, r7, r12, lsr #1     @ g = r7 + delta/2
+                                        @
+#if ARM_ARCH >= 6
+    usat        r11, #5, r11, asr #11   @ clamp r
+    usat        r7, #6, r7, asr #9      @ clamp g
+    usat        r1, #5, r1, asr #10     @ clamp b
+                                        @
+    ldrb        r12, [r4, r3]           @ r12 = Y' = *(Y'_p + stride)
+                                        @
+    orr         r1, r1, r11, lsl #11    @ r1 = b | (r << 11)
+    orr         r1, r1, r7, lsl #5      @ r1 |= (g << 5)
+#else
+    orr         r12, r1, r11, asr #1    @ check if clamping is needed...
+    orr         r12, r12, r7            @ ...at all
+    movs        r12, r12, asr #15       @
+    beq         15f @ no clamp          @
+    movs        r12, r1, asr #15        @ clamp b
+    mvnne       r1, r12, lsr #15        @
+    andne       r1, r1, #0x7c00         @ mask b only if clamped
+    movs        r12, r11, asr #16       @ clamp r
+    mvnne       r11, r12, lsr #16       @
+    movs        r12, r7, asr #15        @ clamp g
+    mvnne       r7, r12, lsr #15        @
+15: @ no clamp                          @
+                                        @
+    ldrb        r12, [r4, r3]           @ r12 = Y' = *(Y'_p + stride)
+                                        @
+    and         r11, r11, #0xf800       @ pack pixel
+    and         r7, r7, #0x7e00         @ r1 = pixel = (r & 0xf800) |
+    orr         r11, r11, r7, lsr #4    @              ((g & 0x7e00) >> 4) |
+    orr         r1, r11, r1, lsr #10    @              (b >> 10)
+#endif
+                                        @
+#if LCD_WIDTH >= LCD_HEIGHT
+    strh        r1, [r0]        @
+#elif LCD_WIDTH < 256
+    strh        r1, [r0], #LCD_WIDTH    @ store pixel
+#else
+    strh        r1, [r0]                @
+#endif
+                                        @
+    sub         r7, r12, #16            @ r7 = Y = (Y' - 16)*149
+    add         r12, r7, r7, asl #2     @
+    add         r12, r12, r12, asl #4   @
+    add         r7, r12, r7, asl #6     @
+                                        @ compute R, G, and B
+    add         r1, r8, r7              @ r1  = b' = Y + bu
+    add         r11, r9, r7, asl #1     @ r11 = r' = Y*2 + rv
+    rsb         r7, r10, r7             @ r7  = g' = Y + guv
+                                        @
+    sub         r12, r1, r1, lsr #5     @ r1  = 31/32*b' + b'/256
+    add         r1, r12, r1, lsr #8     @
+                                        @
+    sub         r12, r11, r11, lsr #5   @ r11 = 31/32*r' + r'/256
+    add         r11, r12, r11, lsr #8   @
+                                        @
+    sub         r12, r7, r7, lsr #6     @ r7  = 63/64*g' + g'/256
+    add         r7, r12, r7, lsr #8     @
+                                        @
+    add         r12, r14, #0x200        @
+                                        @
+    add         r1, r1, r12             @ b = r1 + delta
+    add         r11, r11, r12, lsl #1   @ r = r11 + delta*2
+    add         r7, r7, r12, lsr #1     @ g = r7 + delta/2
+                                        @
+#if ARM_ARCH >= 6
+    usat        r11, #5, r11, asr #11   @ clamp r
+    usat        r7, #6, r7, asr #9      @ clamp g
+    usat        r1, #5, r1, asr #10     @ clamp b
+                                        @
+    ldrb        r12, [r4], #1           @ r12 = Y' = *(Y'_p++)
+                                        @
+    orr         r1, r1, r11, lsl #11    @ r1 = b | (r << 11)
+    orr         r1, r1, r7, lsl #5      @ r1 |= (g << 5)
+#else
+    orr         r12, r1, r11, asr #1    @ check if clamping is needed...
+    orr         r12, r12, r7            @ ...at all
+    movs        r12, r12, asr #15       @
+    beq         15f @ no clamp          @
+    movs        r12, r1, asr #15        @ clamp b
+    mvnne       r1, r12, lsr #15        @
+    andne       r1, r1, #0x7c00         @ mask b only if clamped
+    movs        r12, r11, asr #16       @ clamp r
+    mvnne       r11, r12, lsr #16       @
+    movs        r12, r7, asr #15        @ clamp g
+    mvnne       r7, r12, lsr #15        @
+15: @ no clamp                          @
+                                        @
+    ldrb        r12, [r4], #1           @ r12 = Y' = *(Y'_p++)
+                                        @
+    and         r11, r11, #0xf800       @ pack pixel
+    and         r7, r7, #0x7e00         @ r1 = pixel = (r & 0xf800) |
+    orr         r11, r11, r7, lsr #4    @              ((g & 0x7e00) >> 4) |
+    orr         r1, r11, r1, lsr #10    @              (b >> 10)
+#endif
+                                        @
+#if LCD_WIDTH >= LCD_HEIGHT
+    add         r0, r0, #2*LCD_WIDTH    @
+    strh        r1, [r0]        @ store pixel
+    sub         r0, r0, #2*LCD_WIDTH    @
+#elif LCD_WIDTH < 256
+    strh        r1, [r0, #-LCD_WIDTH-2] @ store pixel
+#else
+    strh        r1, [r0, #-2]           @ store pixel
+    add         r0, r0, #LCD_WIDTH      @
+#endif
+                                        @
+    sub         r7, r12, #16            @ r7 = Y = (Y' - 16)*149
+    add         r12, r7, r7, asl #2     @
+    add         r12, r12, r12, asl #4   @
+    add         r7, r12, r7, asl #6     @
+                                        @ compute R, G, and B
+    add         r1, r8, r7              @ r1  = b' = Y + bu
+    add         r11, r9, r7, asl #1     @ r11 = r' = Y*2 + rv
+    rsb         r7, r10, r7             @ r7  = g' = Y + guv
+                                        @
+                                        @ r8 = bu, r9 = rv, r10 = guv
+                                        @
+    sub         r12, r1, r1, lsr #5     @ r1  = 31/32*b' + b'/256
+    add         r1, r12, r1, lsr #8     @
+                                        @
+    sub         r12, r11, r11, lsr #5   @ r11 = 31/32*r' + r'/256
+    add         r11, r12, r11, lsr #8   @
+                                        @
+    sub         r12, r7, r7, lsr #6     @ r7  = 63/64*g' + g'/256
+    add         r7, r12, r7, lsr #8     @
+                                        @
+    add         r12, r14, #0x300        @
+                                        @
+    add         r1, r1, r12             @ b = r1 + delta
+    add         r11, r11, r12, lsl #1   @ r = r11 + delta*2
+    add         r7, r7, r12, lsr #1     @ g = r7 + delta/2
+                                        @
+#if ARM_ARCH >= 6
+    usat        r11, #5, r11, asr #11   @ clamp r
+    usat        r7, #6, r7, asr #9      @ clamp g
+    usat        r1, #5, r1, asr #10     @ clamp b
+                                        @
+    ldrb        r12, [r4, r3]           @ r12 = Y' = *(Y'_p + stride)
+                                        @
+    orr         r1, r1, r11, lsl #11    @ r1 = b | (r << 11)
+    orr         r1, r1, r7, lsl #5      @ r1 |= (g << 5)
+#else
+    orr         r12, r1, r11, asr #1    @ check if clamping is needed...
+    orr         r12, r12, r7            @ ...at all
+    movs        r12, r12, asr #15       @
+    beq         15f @ no clamp          @
+    movs        r12, r1, asr #15        @ clamp b
+    mvnne       r1, r12, lsr #15        @
+    andne       r1, r1, #0x7c00         @ mask b only if clamped
+    movs        r12, r11, asr #16       @ clamp r
+    mvnne       r11, r12, lsr #16       @
+    movs        r12, r7, asr #15        @ clamp g
+    mvnne       r7, r12, lsr #15        @
+15: @ no clamp                          @
+                                        @
+    ldrb        r12, [r4, r3]           @ r12 = Y' = *(Y'_p + stride)
+                                        @
+    and         r11, r11, #0xf800       @ pack pixel
+    and         r7, r7, #0x7e00         @ r1 = pixel = (r & 0xf800) |
+    orr         r11, r11, r7, lsr #4    @              ((g & 0x7e00) >> 4) |
+    orr         r1, r11, r1, lsr #10    @              (b >> 10)
+#endif
+                                        @
+#if LCD_WIDTH >= LCD_HEIGHT
+    strh        r1, [r0, #2]
+#elif LCD_WIDTH <  256
+    strh        r1, [r0, #LCD_WIDTH]!   @ store pixel
+#else
+    strh        r1, [r0]                @
+#endif
+
+    sub         r7, r12, #16            @ r7 = Y = (Y' - 16)*149
+    add         r12, r7, r7, asl #2     @
+    add         r12, r12, r12, asl #4   @
+    add         r7, r12, r7, asl #6     @
+                                        @ compute R, G, and B
+    add         r1, r8, r7              @ r1  = b' = Y + bu
+    add         r11, r9, r7, asl #1     @ r11 = r' = Y*2 + rv
+    rsb         r7, r10, r7             @ r7  = g' = Y + guv
+                                        @
+    sub         r12, r1, r1, lsr #5     @ r1 = 31/32*b + b/256
+    add         r1, r12, r1, lsr #8     @
+                                        @
+    sub         r12, r11, r11, lsr #5   @ r11 = 31/32*r + r/256
+    add         r11, r12, r11, lsr #8   @
+                                        @
+    sub         r12, r7, r7, lsr #6     @ r7 = 63/64*g + g/256
+    add         r7, r12, r7, lsr #8     @
+                                        @
+    @ This element is zero - use r14    @
+                                        @
+    add         r1, r1, r14             @ b = r1 + delta
+    add         r11, r11, r14, lsl #1   @ r = r11 + delta*2
+    add         r7, r7, r14, lsr #1     @ g = r7 + delta/2
+                                        @
+#if ARM_ARCH >= 6
+    usat        r11, #5, r11, asr #11   @ clamp r
+    usat        r7, #6, r7, asr #9      @ clamp g
+    usat        r1, #5, r1, asr #10     @ clamp b
+                                        @
+    orr         r1, r1, r11, lsl #11    @ r1 = b | (r << 11)
+    orr         r1, r1, r7, lsl #5      @ r1 |= (g << 5)
+#else
+    orr         r12, r1, r11, asr #1    @ check if clamping is needed...
+    orr         r12, r12, r7            @ ...at all
+    movs        r12, r12, asr #15       @
+    beq         15f @ no clamp          @
+    movs        r12, r1, asr #15        @ clamp b
+    mvnne       r1, r12, lsr #15        @
+    andne       r1, r1, #0x7c00         @ mask b only if clamped
+    movs        r12, r11, asr #16       @ clamp r
+    mvnne       r11, r12, lsr #16       @
+    movs        r12, r7, asr #15        @ clamp g
+    mvnne       r7, r12, lsr #15        @
+15: @ no clamp                          @
+                                        @
+    and         r11, r11, #0xf800       @ pack pixel
+    and         r7, r7, #0x7e00         @ r1 = pixel = (r & 0xf800) |
+    orr         r11, r11, r7, lsr #4    @              ((g & 0x7e00) >> 4) |
+    orr         r1, r11, r1, lsr #10    @              (b >> 10)
+#endif
+                                        @
+#if LCD_WIDTH >= LCD_HEIGHT
+    add         r0, r0, #2*LCD_WIDTH
+    strh        r1, [r0, #2]            @ store pixel
+#if LCD_WIDTH <= 512
+    sub         r0, r0, #(2*LCD_WIDTH)-4
+#else
+    sub         r0, r0, #(2*LCD_WIDTH)
+    add         r0, r0, #4
+#endif
+#else
+    strh        r1, [r0, #-2]           @ store pixel
+#if LCD_WIDTH < 256
+    add         r0, r0, #2*LCD_WIDTH    @
+#else
+    add         r0, r0, #LCD_WIDTH      @
+#endif
+#endif
+                                        @
+    subs        r2, r2, #2              @ subtract block from width
+    bgt         10b @ loop line         @
+                                        @
+    ldmpc       regs=r4-r11             @ restore registers and return
+    .ltorg                              @ dump constant pool
+    .size   lcd_write_yuv420_lines_odither, .-lcd_write_yuv420_lines_odither
diff --git a/firmware/asm/lcd-as-memframe.c b/firmware/asm/lcd-as-memframe.c
new file mode 100644
index 0000000000..5f4917b721
--- /dev/null
+++ b/firmware/asm/lcd-as-memframe.c
@@ -0,0 +1,181 @@
+
+#include <string.h>
+#include "lcd.h"
+void lcd_copy_buffer_rect(fb_data *dst, fb_data *src, int width, int height)
+{
+    do {
+        memcpy(dst, src, width * sizeof(fb_data));
+        src += LCD_WIDTH;
+        dst += LCD_WIDTH;
+    } while (--height);
+}
+
+#define YFAC    (74)
+#define RVFAC   (101)
+#define GUFAC   (-24)
+#define GVFAC   (-51)
+#define BUFAC   (128)
+
+static inline int clamp(int val, int min, int max)
+{
+    if (val < min)
+        val = min;
+    else if (val > max)
+        val = max;
+    return val;
+}
+
+extern void lcd_write_yuv420_lines(fb_data *dst,
+                                   unsigned char const * const src[3],
+                                   int width,
+                                   int stride)
+{
+    /* Draw a partial YUV colour bitmap - similiar behavior to lcd_blit_yuv
+       in the core */
+    const unsigned char *ysrc, *usrc, *vsrc;
+    int height = 2, linecounter;
+    fb_data *row_end;
+
+    /* width and height must be >= 2 and an even number */
+    width &= ~1;
+    linecounter = height >> 1;
+
+#if LCD_WIDTH >= LCD_HEIGHT
+    row_end = dst + width;
+#else
+    row_end = dst + LCD_WIDTH * width;
+#endif
+
+    ysrc = src[0];
+    usrc = src[1];
+    vsrc = src[2];
+
+    /* stride => amount to jump from end of last row to start of next */
+    stride -= width;
+
+    /* upsampling, YUV->RGB conversion and reduction to RGB565 in one go */
+
+    do
+    {
+        int y, cb, cr, rv, guv, bu, r, g, b;
+
+        y  = YFAC*(*ysrc++ - 16);
+        cb = *usrc++ - 128;
+        cr = *vsrc++ - 128;
+
+        rv  =            RVFAC*cr;
+        guv = GUFAC*cb + GVFAC*cr;
+        bu  = BUFAC*cb;
+
+        r = y + rv;
+        g = y + guv;
+        b = y + bu;
+
+        if ((unsigned)(r | g | b) > 64*256-1)
+        {
+            r = clamp(r, 0, 64*256-1);
+            g = clamp(g, 0, 64*256-1);
+            b = clamp(b, 0, 64*256-1);
+        }
+
+        *dst = LCD_RGBPACK_LCD(r >> 9, g >> 8, b >> 9);
+
+#if LCD_WIDTH >= LCD_HEIGHT
+        dst++;
+#else
+        dst += LCD_WIDTH;
+#endif
+
+        y = YFAC*(*ysrc++ - 16);
+        r = y + rv;
+        g = y + guv;
+        b = y + bu;
+
+        if ((unsigned)(r | g | b) > 64*256-1)
+        {
+            r = clamp(r, 0, 64*256-1);
+            g = clamp(g, 0, 64*256-1);
+            b = clamp(b, 0, 64*256-1);
+        }
+
+        *dst = LCD_RGBPACK_LCD(r >> 9, g >> 8, b >> 9);
+
+#if LCD_WIDTH >= LCD_HEIGHT
+        dst++;
+#else
+        dst += LCD_WIDTH;
+#endif
+    }
+    while (dst < row_end);
+
+    ysrc    += stride;
+    usrc    -= width >> 1;
+    vsrc    -= width >> 1;
+
+#if LCD_WIDTH >= LCD_HEIGHT
+    row_end += LCD_WIDTH;
+    dst     += LCD_WIDTH - width;
+#else
+    row_end -= 1;
+    dst     -= LCD_WIDTH*width + 1;
+#endif
+
+    do
+    {
+        int y, cb, cr, rv, guv, bu, r, g, b;
+
+        y  = YFAC*(*ysrc++ - 16);
+        cb = *usrc++ - 128;
+        cr = *vsrc++ - 128;
+
+        rv  =            RVFAC*cr;
+        guv = GUFAC*cb + GVFAC*cr;
+        bu  = BUFAC*cb;
+
+        r = y + rv;
+        g = y + guv;
+        b = y + bu;
+
+        if ((unsigned)(r | g | b) > 64*256-1)
+        {
+            r = clamp(r, 0, 64*256-1);
+            g = clamp(g, 0, 64*256-1);
+            b = clamp(b, 0, 64*256-1);
+        }
+
+        *dst = LCD_RGBPACK_LCD(r >> 9, g >> 8, b >> 9);
+
+#if LCD_WIDTH >= LCD_HEIGHT
+        dst++;
+#else
+        dst += LCD_WIDTH;
+#endif
+
+        y = YFAC*(*ysrc++ - 16);
+        r = y + rv;
+        g = y + guv;
+        b = y + bu;
+
+        if ((unsigned)(r | g | b) > 64*256-1)
+        {
+            r = clamp(r, 0, 64*256-1);
+            g = clamp(g, 0, 64*256-1);
+            b = clamp(b, 0, 64*256-1);
+        }
+
+        *dst = LCD_RGBPACK_LCD(r >> 9, g >> 8, b >> 9);
+
+#if LCD_WIDTH >= LCD_HEIGHT
+        dst++;
+#else
+        dst += LCD_WIDTH;
+#endif
+    }
+    while (dst < row_end);
+}
+
+void lcd_write_yuv420_lines_odither(fb_data *dst,
+                                   unsigned char const * const src[3],
+                                   int width, int stride,
+                                   int x_screen, int y_screen)
+__attribute__((alias("lcd_write_yuv420_lines")));