x86/lpc: implement a new Welch windowing function

Old one was written with the assumption only even inputs would be given.
This very messy replacement supports even and odd inputs, and supports
AVX2 for extra speed. The buffers given are usually quite big (4k samples),
so the speedup is worth it.
The new SSE version is still faster than the old inline asm version by 33%.

Also checkasm is provided to make sure this monstrosity works.

This fixes some FATE tests.

4 files changed, 85 insertions, 0 deletions

diff --git a/tests/checkasm/Makefile b/tests/checkasm/Makefile
index ac02670e64..f330d3a8ab 100644
--- a/tests/checkasm/Makefile
+++ b/tests/checkasm/Makefile
@@ -11,6 +11,7 @@ AVCODECOBJS-$(CONFIG_H264QPEL)          += h264qpel.o
 AVCODECOBJS-$(CONFIG_IDCTDSP)           += idctdsp.o
 AVCODECOBJS-$(CONFIG_LLVIDDSP)          += llviddsp.o
 AVCODECOBJS-$(CONFIG_LLVIDENCDSP)       += llviddspenc.o
+AVCODECOBJS-$(CONFIG_LPC)               += lpc.o
 AVCODECOBJS-$(CONFIG_ME_CMP)            += motion.o
 AVCODECOBJS-$(CONFIG_VC1DSP)            += vc1dsp.o
 AVCODECOBJS-$(CONFIG_VP8DSP)            += vp8dsp.o
diff --git a/tests/checkasm/checkasm.c b/tests/checkasm/checkasm.c
index 6b4a0f22b2..8fd9bba0b0 100644
--- a/tests/checkasm/checkasm.c
+++ b/tests/checkasm/checkasm.c
@@ -135,6 +135,9 @@ static const struct {
     #if CONFIG_LLVIDENCDSP
         { "llviddspenc", checkasm_check_llviddspenc },
     #endif
+    #if CONFIG_LPC
+        { "lpc", checkasm_check_lpc },
+    #endif
     #if CONFIG_ME_CMP
         { "motion", checkasm_check_motion },
     #endif
diff --git a/tests/checkasm/checkasm.h b/tests/checkasm/checkasm.h
index 171dd06b47..97e909170f 100644
--- a/tests/checkasm/checkasm.h
+++ b/tests/checkasm/checkasm.h
@@ -68,6 +68,7 @@ void checkasm_check_idctdsp(void);
 void checkasm_check_jpeg2000dsp(void);
 void checkasm_check_llviddsp(void);
 void checkasm_check_llviddspenc(void);
+void checkasm_check_lpc(void);
 void checkasm_check_motion(void);
 void checkasm_check_nlmeans(void);
 void checkasm_check_opusdsp(void);
diff --git a/tests/checkasm/lpc.c b/tests/checkasm/lpc.c
new file mode 100644
index 0000000000..b68ce05bfa
--- /dev/null
+++ b/tests/checkasm/lpc.c
@@ -0,0 +1,80 @@
+/*
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg 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.
+ *
+ * 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU 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 "libavutil/mem_internal.h"
+
+#include "libavcodec/lpc.h"
+
+#include "checkasm.h"
+
+#define randomize_int32(buf, len)       \
+    do {                                \
+        for (int i = 0; i < len; i++) { \
+            int32_t f = rnd() >> 8;     \
+            buf[i] = f;                 \
+        }                               \
+    } while (0)
+
+#define EPS 0.005
+
+static void test_window(int len)
+{
+    LOCAL_ALIGNED(16, int32_t, src, [5000]);
+    LOCAL_ALIGNED(16, double, dst0, [5000]);
+    LOCAL_ALIGNED(16, double, dst1, [5000]);
+
+    declare_func(void, int32_t *in, int len, double *out);
+
+    randomize_int32(src, len);
+
+    call_ref(src, len, dst0);
+    call_new(src, len, dst1);
+
+    if (!double_near_abs_eps_array(dst0, dst1, EPS, len))
+        fail();
+
+    bench_new(src, len, dst1);
+}
+
+void checkasm_check_lpc(void)
+{
+    LPCContext ctx;
+    ff_lpc_init(&ctx, 32, 16, FF_LPC_TYPE_DEFAULT);
+
+    if (check_func(ctx.lpc_apply_welch_window, "apply_welch_window_even")) {
+        for (int i = 0; i < 64; i += 2)
+            test_window(i);
+    }
+    report("apply_welch_window_even");
+
+    if (check_func(ctx.lpc_apply_welch_window, "apply_welch_window_odd")) {
+        for (int i = 1; i < 64; i += 2)
+            test_window(i);
+    }
+    report("apply_welch_window_odd");
+
+    if (check_func(ctx.lpc_apply_welch_window, "apply_welch_window_4096"))
+        test_window(4096);
+    report("apply_welch_window_4096");
+
+    if (check_func(ctx.lpc_apply_welch_window, "apply_welch_window_4097"))
+        test_window(4097);
+    report("apply_welch_window_4097");
+
+    ff_lpc_end(&ctx);
+}