On date Saturday 2015-06-13 14:20:07 +0200, Hendrik Leppkes encoded:
> On Thu, Jun 11, 2015 at 8:54 PM, wm4 <nfx...@googlemail.com> wrote:
> > On Thu, 11 Jun 2015 17:24:45 +0200
> > Stefano Sabatini <stefa...@gmail.com> wrote:
> >
> >> Next step would be the use of YASM, but I only want to test if the
> >> general approach is fine (and if the API is not too specific). Also if
> >> someone wants to step up and port it to YASM I'm all for it, since
> >> ASM/YASM is far from being my area of expertise.
> >
> > Personally, I'd probably just
> > 1. export the GPU memcpy function, and
> > 2. export a function to copy AVFrames using this function
>
> I concur. A basic optimized memcpy with specific constraints (ie.
> requires aligned input/output, always copies in 16-byte chunks, so
> in/out buffers need to be padded appropriately), to keep the required
> ASM code simple.
> These constraints are generally always fulfilled if you have a GPU
> frame on the input, since they will have appropriate strides (and if
> in question, we control allocation of the GPU surfaces as well), and
> we control the output memory buffer anyway.
>
> On top of that a convenience function that deals with pixel formats,
> strides, planes, and whatnot, and then uses this function.
> A generic C version of the basic copy function shouldn't be needed, we
> could just use memcpy for that.. or a tiny wrapper that calls memcpy,
> anyway.
This is my first attempt, the added function is named av_memcpynt(),
it is using inline assembly which should be replaced by yasm once me
or someone else figures out how to do it.
An av_image_copynt_plane() function can be built on top of that (but
in this case it would be better to inline the av_memcpynt() function).
BTW I dropped the requirement of 16-bits alignment on the size
variable which is required by the VLC code but which looks unnecessary
to me.
--
FFmpeg = Furious and Foolish Marvellous Pacific Egregious Ghost
>From 3a75ef1e86360cd6f30b8e550307404d0d1c1dba Mon Sep 17 00:00:00 2001
From: Stefano Sabatini <stefa...@gmail.com>
Date: Mon, 15 Jun 2015 11:02:50 +0200
Subject: [PATCH] lavu/mem: add av_memcpynt() function with x86 optimizations
Assembly based on code from vlc dxva2.c, commit 62107e56 by Laurent Aimar
<fen...@videolan.org>.
TODO: bump minor, update APIchanges
---
libavutil/mem.c | 9 +++++
libavutil/mem.h | 14 ++++++++
libavutil/mem_internal.h | 26 +++++++++++++++
libavutil/x86/Makefile | 1 +
libavutil/x86/mem.c | 85 ++++++++++++++++++++++++++++++++++++++++++++++++
5 files changed, 135 insertions(+)
create mode 100644 libavutil/mem_internal.h
create mode 100644 libavutil/x86/mem.c
diff --git a/libavutil/mem.c b/libavutil/mem.c
index da291fb..0e1eb01 100644
--- a/libavutil/mem.c
+++ b/libavutil/mem.c
@@ -42,6 +42,7 @@
#include "dynarray.h"
#include "intreadwrite.h"
#include "mem.h"
+#include "mem_internal.h"
#ifdef MALLOC_PREFIX
@@ -515,3 +516,11 @@ void av_fast_malloc(void *ptr, unsigned int *size, size_t min_size)
ff_fast_malloc(ptr, size, min_size, 0);
}
+void av_memcpynt(void *dst, const void *src, size_t size, int cpu_flags)
+{
+#if ARCH_X86
+ ff_memcpynt_x86(dst, src, size, cpu_flags);
+#else
+ memcpy(dst, src, size, cpu_flags);
+#endif
+}
diff --git a/libavutil/mem.h b/libavutil/mem.h
index 2a1e36d..bbad313 100644
--- a/libavutil/mem.h
+++ b/libavutil/mem.h
@@ -383,6 +383,20 @@ void *av_fast_realloc(void *ptr, unsigned int *size, size_t min_size);
void av_fast_malloc(void *ptr, unsigned int *size, size_t min_size);
/**
+ * Copy size bytes from from src to dst, using non-temporal copy
+ * functions when available.
+ *
+ * This function works as memcpy, but adopts non-temporal instructios
+ * when available. This can lead to better performances when
+ * transferring data from source to destination is expensive, for
+ * example when reading from GPU memory.
+ *
+ * @param dst destination memory pointer, must be aligned to 16 bits
+ * @param cpu_flags as returned by av_get_cpu_flags()
+ */
+void av_memcpynt(void *dst, const void *src, size_t size, int cpu_flags);
+
+/**
* @}
*/
diff --git a/libavutil/mem_internal.h b/libavutil/mem_internal.h
new file mode 100644
index 0000000..371be31
--- /dev/null
+++ b/libavutil/mem_internal.h
@@ -0,0 +1,26 @@
+/*
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef AVUTIL_MEM_INTERNAL_H
+#define AVUTIL_MEM_INTERNAL_H
+
+#include "mem.h"
+
+void ff_memcpynt_x86(void *dst, const void *src, size_t size, int cpu_flags);
+
+#endif /* AVUTIL_MEM_INTERNAL_H */
diff --git a/libavutil/x86/Makefile b/libavutil/x86/Makefile
index a719c00..171c351 100644
--- a/libavutil/x86/Makefile
+++ b/libavutil/x86/Makefile
@@ -2,6 +2,7 @@ OBJS += x86/cpu.o \
x86/float_dsp_init.o \
x86/imgutils.o \
x86/lls_init.o \
+ x86/mem.o \
OBJS-$(CONFIG_PIXELUTILS) += x86/pixelutils_init.o \
diff --git a/libavutil/x86/mem.c b/libavutil/x86/mem.c
new file mode 100644
index 0000000..fef3b7f
--- /dev/null
+++ b/libavutil/x86/mem.c
@@ -0,0 +1,85 @@
+/*
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <inttypes.h>
+#include "config.h"
+#include "libavutil/avassert.h"
+#include "libavutil/mem_internal.h"
+
+#if HAVE_SSE2
+/* Copy 16/64 bytes from srcp to dstp loading data with the SSE>=2 instruction
+ * load and storing data with the SSE>=2 instruction store.
+ */
+#define COPY16(dstp, srcp, load, store) \
+ __asm__ volatile ( \
+ load " 0(%[src]), %%xmm1\n" \
+ store " %%xmm1, 0(%[dst])\n" \
+ : : [dst]"r"(dstp), [src]"r"(srcp) : "memory", "xmm1")
+
+#define COPY64(dstp, srcp, load, store) \
+ __asm__ volatile ( \
+ load " 0(%[src]), %%xmm1\n" \
+ load " 16(%[src]), %%xmm2\n" \
+ load " 32(%[src]), %%xmm3\n" \
+ load " 48(%[src]), %%xmm4\n" \
+ store " %%xmm1, 0(%[dst])\n" \
+ store " %%xmm2, 16(%[dst])\n" \
+ store " %%xmm3, 32(%[dst])\n" \
+ store " %%xmm4, 48(%[dst])\n" \
+ : : [dst]"r"(dstp), [src]"r"(srcp) : "memory", "xmm1", "xmm2", "xmm3", "xmm4")
+#endif
+
+#define COPY_LINE(dstp, srcp, size, load) \
+ const unsigned unaligned = (-(uintptr_t)srcp) & 0x0f; \
+ unsigned x = unaligned; \
+ \
+ av_assert0(((intptr_t)dstp & 0x0f) == 0); \
+ \
+ __asm__ volatile ("mfence"); \
+ if (!unaligned) { \
+ for (; x+63 < size; x += 64) \
+ COPY64(&dstp[x], &srcp[x], load, "movdqa"); \
+ } else { \
+ COPY16(dst, src, "movdqu", "movdqa"); \
+ for (; x+63 < size; x += 64) \
+ COPY64(&dstp[x], &srcp[x], load, "movdqu"); \
+ } \
+ \
+ for (; x < size; x++) \
+ dstp[x] = srcp[x]; \
+ __asm__ volatile ("mfence");
+
+void ff_memcpynt_x86(void *dst, const void *src, size_t size, int cpu_flags)
+{
+ uint8_t *dstu = dst;
+ const uint8_t *srcu = src;
+
+#if HAVE_SSE4
+ if (cpu_flags & AV_CPU_FLAG_SSE4) {
+ COPY_LINE(dstu, srcu, size, "movntdqa");
+ return;
+ }
+#endif
+#if HAVE_SSE2
+ if (cpu_flags & AV_CPU_FLAG_SSE2) {
+ COPY_LINE(dstu, srcu, size, "movdqa");
+ return;
+ }
+#endif
+ memcpy(dst, src, size);
+}
--
1.9.1
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