/*
* Copyright © 2009 Nokia Corporation
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*
* Author: Siarhei Siamashka (siarhei.siamashka@nokia.com)
*/
/*
* This file contains implementations of NEON optimized pixel processing
* functions. There is no full and detailed tutorial, but some functions
* (those which are exposing some new or interesting features) are
* extensively commented and can be used as examples.
*
* You may want to have a look at the comments for following functions:
* - pixman_composite_over_8888_0565_asm_neon
* - pixman_composite_over_n_8_0565_asm_neon
*/
/* Prevent the stack from becoming executable for no reason... */
#if defined(__linux__) && defined(__ELF__)
.section .note.GNU-stack,"",%progbits
#endif
.text
.fpu neon
.arch armv7a
.object_arch armv4
.eabi_attribute 10, 0 /* suppress Tag_FP_arch */
.eabi_attribute 12, 0 /* suppress Tag_Advanced_SIMD_arch */
.arm
.altmacro
.p2align 2
//#include "pixman-arm-asm.h"
/* Supplementary macro for setting function attributes */
.macro pixman_asm_function fname
.func fname
.global fname
#ifdef __ELF__
.hidden fname
.type fname, %function
#endif
fname:
.endm
//#include "pixman-private.h"
/*
* The defines which are shared between C and assembly code
*/
/* bilinear interpolation precision (must be < 8) */
#define BILINEAR_INTERPOLATION_BITS 7
#define BILINEAR_INTERPOLATION_RANGE (1 << BILINEAR_INTERPOLATION_BITS)
#include "pixman-arm-neon-asm.h"
/* Global configuration options and preferences */
/*
* The code can optionally make use of unaligned memory accesses to improve
* performance of handling leading/trailing pixels for each scanline.
* Configuration variable RESPECT_STRICT_ALIGNMENT can be set to 0 for
* example in linux if unaligned memory accesses are not configured to
* generate.exceptions.
*/
.set RESPECT_STRICT_ALIGNMENT, 1
/*
* Set default prefetch type. There is a choice between the following options:
*
* PREFETCH_TYPE_NONE (may be useful for the ARM cores where PLD is set to work
* as NOP to workaround some HW bugs or for whatever other reason)
*
* PREFETCH_TYPE_SIMPLE (may be useful for simple single-issue ARM cores where
* advanced prefetch intruduces heavy overhead)
*
* PREFETCH_TYPE_ADVANCED (useful for superscalar cores such as ARM Cortex-A8
* which can run ARM and NEON instructions simultaneously so that extra ARM
* instructions do not add (many) extra cycles, but improve prefetch efficiency)
*
* Note: some types of function can't support advanced prefetch and fallback
* to simple one (those which handle 24bpp pixels)
*/
.set PREFETCH_TYPE_DEFAULT, PREFETCH_TYPE_ADVANCED
/* Prefetch distance in pixels for simple prefetch */
.set PREFETCH_DISTANCE_SIMPLE, 64
/*
* Implementation of pixman_composite_over_8888_0565_asm_neon
*
* This function takes a8r8g8b8 source buffer, r5g6b5 destination buffer and
* performs OVER compositing operation. Function fast_composite_over_8888_0565
* from pixman-fast-path.c does the same in C and can be used as a reference.
*
* First we need to have some NEON assembly code which can do the actual
* operation on the pixels and provide it to the template macro.
*
* Template macro quite conveniently takes care of emitting all the necessary
* code for memory reading and writing (including quite tricky cases of
* handling unaligned leading/trailing pixels), so we only need to deal with
* the data in NEON registers.
*
* NEON registers allocation in general is recommented to be the following:
* d0, d1, d2, d3 - contain loaded source pixel data
* d4, d5, d6, d7 - contain loaded destination pixels (if they are needed)
* d24, d25, d26, d27 - contain loading mask pixel data (if mask is used)
* d28, d29, d30, d31 - place for storing the result (destination pixels)
*
* As can be seen above, four 64-bit NEON registers are used for keeping
* intermediate pixel data and up to 8 pixels can be processed in one step
* for 32bpp formats (16 pixels for 16bpp, 32 pixels for 8bpp).
*
* This particular function uses the following registers allocation:
* d0, d1, d2, d3 - contain loaded source pixel data
* d4, d5 - contain loaded destination pixels (they are needed)
* d28, d29 - place for storing the result (destination pixels)
*/
/*
* Step one. We need to have some code to do some arithmetics on pixel data.
* This is implemented as a pair of macros: '*_head' and '*_tail'. When used
* back-to-back, they take pixel data from {d0, d1, d2, d3} and {d4, d5},
* perform all the needed calculations and write the result to {d28, d29}.
* The rationale for having two macros and not just one will be explained
* later. In practice, any single monolitic function which does the work can
* be split into two parts in any arbitrary way without affecting correctness.
*
* There is one special trick here too. Common template macro can optionally
* make our life a bit easier by doing R, G, B, A color components
* deinterleaving for 32bpp pixel formats (and this feature is used in
* 'pixman_composite_over_8888_0565_asm_neon' function). So it means that
* instead of having 8 packed pixels in {d0, d1, d2, d3} registers, we
* actually use d0 register for blue channel (a vector of eight 8-bit
* values), d1 register for green, d2 for red and d3 for alpha. This
* simple conversion can be also done with a few NEON instructions:
*
* Packed to planar conversion:
* vuzp.8 d0, d1
* vuzp.8 d2, d3
* vuzp.8 d1, d3
* vuzp.8 d0, d2
*
* Planar to packed conversion:
* vzip.8 d0, d2
* vzip.8 d1, d3
* vzip.8 d2, d3
* vzip.8 d0, d1
*
* But pixel can be loaded directly in planar format using VLD4.8 NEON
* instruction. It is 1 cycle slower than VLD1.32, so this is not always
* desirable, that's why deinterleaving is optional.
*
* But anyway, here is the code:
*/
/*
* OK, now we got almost everything that we need. Using the above two
* macros, the work can be done right. But now we want to optimize
* it a bit. ARM Cortex-A8 is an in-order core, and benefits really
* a lot from good code scheduling and software pipelining.
*
* Let's construct some code, which will run in the core main loop.
* Some pseudo-code of the main loop will look like this:
* head
* while (...) {
* tail
* head
* }
* tail
*
* It may look a bit weird, but this setup allows to hide instruction
* latencies better and also utilize dual-issue capability more
* efficiently (make pairs of load-store and ALU instructions).
*
* So what we need now is a '*_tail_head' macro, which will be used
* in the core main loop. A trivial straightforward implementation
* of this macro would look like this:
*
* pixman_composite_over_8888_0565_process_pixblock_tail
* vst1.16 {d28, d29}, [DST_W, :128]!
* vld1.16 {d4, d5}, [DST_R, :128]!
* vld4.32 {d0, d1, d2, d3}, [SRC]!
* pixman_composite_over_8888_0565_process_pixblock_head
* cache_preload 8, 8
*
* Now it also got some VLD/VST instructions. We simply can't move from
* processing one block of pixels to the other one with just arithmetics.
* The previously processed data needs to be written to memory and new
* data needs to be fetched. Fortunately, this main loop does not deal
* with partial leading/trailing pixels and can load/store a full block
* of pixels in a bulk. Additionally, destination buffer is already
* 16 bytes aligned here (which is good for performance).
*
* New things here are DST_R, DST_W, SRC and MASK identifiers. These
* are the aliases for ARM registers which are used as pointers for
* accessing data. We maintain separate pointers for reading and writing
* destination buffer (DST_R and DST_W).
*
* Another new thing is 'cache_preload' macro. It is used for prefetching
* data into CPU L2 cache and improve performance when dealing with large
* images which are far larger than cache size. It uses one argument
* (actually two, but they need to be the same here) - number of pixels
* in a block. Looking into 'pixman-arm-neon-asm.h' can provide some
* details about this macro. Moreover, if good performance is needed
* the code from this macro needs to be copied into '*_tail_head' macro
* and mixed with the rest of code for optimal instructions scheduling.
* We are actually doing it below.
*
* Now after all the explanations, here is the optimized code.
* Different instruction streams (originaling from '*_head', '*_tail'
* and 'cache_preload' macro) use different indentation levels for
* better readability. Actually taking the code from one of these
* indentation levels and ignoring a few VLD/VST instructions would
* result in exactly the code from '*_head', '*_tail' or 'cache_preload'
* macro!
*/
/*
* And now the final part. We are using 'generate_composite_function' macro
* to put all the stuff together. We are specifying the name of the function
* which we want to get, number of bits per pixel for the source, mask and
* destination (0 if unused, like mask in this case). Next come some bit
* flags:
* FLAG_DST_READWRITE - tells that the destination buffer is both read
* and written, for write-only buffer we would use
* FLAG_DST_WRITEONLY flag instead
* FLAG_DEINTERLEAVE_32BPP - tells that we prefer to work with planar data
* and separate color channels for 32bpp format.
* The next things are:
* - the number of pixels processed per iteration (8 in this case, because
* that's the maximum what can fit into four 64-bit NEON registers).
* - prefetch distance, measured in pixel blocks. In this case it is 5 times
* by 8 pixels. That would be 40 pixels, or up to 160 bytes. Optimal
* prefetch distance can be selected by running some benchmarks.
*
* After that we specify some macros, these are 'default_init',
* 'default_cleanup' here which are empty (but it is possible to have custom
* init/cleanup macros to be able to save/restore some extra NEON registers
* like d8-d15 or do anything else) followed by
* 'pixman_composite_over_8888_0565_process_pixblock_head',
* 'pixman_composite_over_8888_0565_process_pixblock_tail' and
* 'pixman_composite_over_8888_0565_process_pixblock_tail_head'
* which we got implemented above.
*
* The last part is the NEON registers allocation scheme.
*/
/******************************************************************************/
/******************************************************************************/
.macro pixman_composite_out_reverse_8888_8888_process_pixblock_head
vmvn.8 d24, d3 /* get inverted alpha */
/* do alpha blending */
vmull.u8 q8, d24, d4
vmull.u8 q9, d24, d5
vmull.u8 q10, d24, d6
vmull.u8 q11, d24, d7
.endm
.macro pixman_composite_out_reverse_8888_8888_process_pixblock_tail
vrshr.u16 q14, q8, #8
vrshr.u16 q15, q9, #8
vrshr.u16 q12, q10, #8
vrshr.u16 q13, q11, #8
vraddhn.u16 d28, q14, q8
vraddhn.u16 d29, q15, q9
vraddhn.u16 d30, q12, q10
vraddhn.u16 d31, q13, q11
.endm
/******************************************************************************/
.macro pixman_composite_over_8888_8888_process_pixblock_head
pixman_composite_out_reverse_8888_8888_process_pixblock_head
.endm
.macro pixman_composite_over_8888_8888_process_pixblock_tail
pixman_composite_out_reverse_8888_8888_process_pixblock_tail
vqadd.u8 q14, q0, q14
vqadd.u8 q15, q1, q15
.endm
.macro pixman_composite_over_8888_8888_process_pixblock_tail_head
vld4.8 {d4, d5, d6, d7}, [DST_R, :128]!
vrshr.u16 q14, q8, #8
PF add PF_X, PF_X, #8
PF tst PF_CTL, #0xF
vrshr.u16 q15, q9, #8
vrshr.u16 q12, q10, #8
vrshr.u16 q13, q11, #8
PF addne PF_X, PF_X, #8
PF subne PF_CTL, PF_CTL, #1
vraddhn.u16 d28, q14, q8
vraddhn.u16 d29, q15, q9
PF cmp PF_X, ORIG_W
vraddhn.u16 d30, q12, q10
vraddhn.u16 d31, q13, q11
vqadd.u8 q14, q0, q14
vqadd.u8 q15, q1, q15
fetch_src_pixblock
PF pld, [PF_SRC, PF_X, lsl #src_bpp_shift]
vmvn.8 d22, d3
PF pld, [PF_DST, PF_X, lsl #dst_bpp_shift]
vst4.8 {d28, d29, d30, d31}, [DST_W, :128]!
PF subge PF_X, PF_X, ORIG_W
vmull.u8 q8, d22, d4
PF subges PF_CTL, PF_CTL, #0x10
vmull.u8 q9, d22, d5
PF ldrgeb DUMMY, [PF_SRC, SRC_STRIDE, lsl #src_bpp_shift]!
vmull.u8 q10, d22, d6
PF ldrgeb DUMMY, [PF_DST, DST_STRIDE, lsl #dst_bpp_shift]!
vmull.u8 q11, d22, d7
.endm
generate_composite_function \
pixman_composite_over_8888_8888_asm_neon, 32, 0, 32, \
FLAG_DST_READWRITE | FLAG_DEINTERLEAVE_32BPP, \
8, /* number of pixels, processed in a single block */ \
5, /* prefetch distance */ \
default_init, \
default_cleanup, \
pixman_composite_over_8888_8888_process_pixblock_head, \
pixman_composite_over_8888_8888_process_pixblock_tail, \
pixman_composite_over_8888_8888_process_pixblock_tail_head
generate_composite_function_single_scanline \
pixman_composite_scanline_over_asm_neon, 32, 0, 32, \
FLAG_DST_READWRITE | FLAG_DEINTERLEAVE_32BPP, \
8, /* number of pixels, processed in a single block */ \
default_init, \
default_cleanup, \
pixman_composite_over_8888_8888_process_pixblock_head, \
pixman_composite_over_8888_8888_process_pixblock_tail, \
pixman_composite_over_8888_8888_process_pixblock_tail_head
/******************************************************************************/
.macro pixman_composite_over_n_8888_process_pixblock_head
/* deinterleaved source pixels in {d0, d1, d2, d3} */
/* inverted alpha in {d24} */
/* destination pixels in {d4, d5, d6, d7} */
vmull.u8 q8, d24, d4
vmull.u8 q9, d24, d5
vmull.u8 q10, d24, d6
vmull.u8 q11, d24, d7
.endm
.macro pixman_composite_over_n_8888_process_pixblock_tail
vrshr.u16 q14, q8, #8
vrshr.u16 q15, q9, #8
vrshr.u16 q2, q10, #8
vrshr.u16 q3, q11, #8
vraddhn.u16 d28, q14, q8
vraddhn.u16 d29, q15, q9
vraddhn.u16 d30, q2, q10
vraddhn.u16 d31, q3, q11
vqadd.u8 q14, q0, q14
vqadd.u8 q15, q1, q15
.endm
.macro pixman_composite_over_n_8888_process_pixblock_tail_head
vrshr.u16 q14, q8, #8
vrshr.u16 q15, q9, #8
vrshr.u16 q2, q10, #8
vrshr.u16 q3, q11, #8
vraddhn.u16 d28, q14, q8
vraddhn.u16 d29, q15, q9
vraddhn.u16 d30, q2, q10
vraddhn.u16 d31, q3, q11
vld4.8 {d4, d5, d6, d7}, [DST_R, :128]!
vqadd.u8 q14, q0, q14
PF add PF_X, PF_X, #8
PF tst PF_CTL, #0x0F
PF addne PF_X, PF_X, #8
PF subne PF_CTL, PF_CTL, #1
vqadd.u8 q15, q1, q15
PF cmp PF_X, ORIG_W
vmull.u8 q8, d24, d4
PF pld, [PF_DST, PF_X, lsl #dst_bpp_shift]
vmull.u8 q9, d24, d5
PF subge PF_X, PF_X, ORIG_W
vmull.u8 q10, d24, d6
PF subges PF_CTL, PF_CTL, #0x10
vmull.u8 q11, d24, d7
PF ldrgeb DUMMY, [PF_DST, DST_STRIDE, lsl #dst_bpp_shift]!
vst4.8 {d28, d29, d30, d31}, [DST_W, :128]!
.endm
.macro pixman_composite_over_n_8888_init
add DUMMY, sp, #ARGS_STACK_OFFSET
vld1.32 {d3[0]}, [DUMMY]
vdup.8 d0, d3[0]
vdup.8 d1, d3[1]
vdup.8 d2, d3[2]
vdup.8 d3, d3[3]
vmvn.8 d24, d3 /* get inverted alpha */
.endm
generate_composite_function \
pixman_composite_over_n_8888_asm_neon, 0, 0, 32, \
FLAG_DST_READWRITE | FLAG_DEINTERLEAVE_32BPP, \
8, /* number of pixels, processed in a single block */ \
5, /* prefetch distance */ \
pixman_composite_over_n_8888_init, \
default_cleanup, \
pixman_composite_over_8888_8888_process_pixblock_head, \
pixman_composite_over_8888_8888_process_pixblock_tail, \
pixman_composite_over_n_8888_process_pixblock_tail_head
/******************************************************************************/
.macro pixman_composite_src_n_8888_process_pixblock_head
.endm
.macro pixman_composite_src_n_8888_process_pixblock_tail
.endm
.macro pixman_composite_src_n_8888_process_pixblock_tail_head
vst1.32 {d0, d1, d2, d3}, [DST_W, :128]!
.endm
.macro pixman_composite_src_n_8888_init
add DUMMY, sp, #ARGS_STACK_OFFSET
vld1.32 {d0[0]}, [DUMMY]
vsli.u64 d0, d0, #32
vorr d1, d0, d0
vorr q1, q0, q0
.endm
.macro pixman_composite_src_n_8888_cleanup
.endm
generate_composite_function \
pixman_composite_src_n_8888_asm_neon, 0, 0, 32, \
FLAG_DST_WRITEONLY, \
8, /* number of pixels, processed in a single block */ \
0, /* prefetch distance */ \
pixman_composite_src_n_8888_init, \
pixman_composite_src_n_8888_cleanup, \
pixman_composite_src_n_8888_process_pixblock_head, \
pixman_composite_src_n_8888_process_pixblock_tail, \
pixman_composite_src_n_8888_process_pixblock_tail_head, \
0, /* dst_w_basereg */ \
0, /* dst_r_basereg */ \
0, /* src_basereg */ \
0 /* mask_basereg */
/******************************************************************************/
.macro pixman_composite_src_8888_8888_process_pixblock_head
.endm
.macro pixman_composite_src_8888_8888_process_pixblock_tail
.endm
.macro pixman_composite_src_8888_8888_process_pixblock_tail_head
vst1.32 {d0, d1, d2, d3}, [DST_W, :128]!
fetch_src_pixblock
cache_preload 8, 8
.endm
generate_composite_function \
pixman_composite_src_8888_8888_asm_neon, 32, 0, 32, \
FLAG_DST_WRITEONLY, \
8, /* number of pixels, processed in a single block */ \
10, /* prefetch distance */ \
default_init, \
default_cleanup, \
pixman_composite_src_8888_8888_process_pixblock_head, \
pixman_composite_src_8888_8888_process_pixblock_tail, \
pixman_composite_src_8888_8888_process_pixblock_tail_head, \
0, /* dst_w_basereg */ \
0, /* dst_r_basereg */ \
0, /* src_basereg */ \
0 /* mask_basereg */
/******************************************************************************/