Implement shrinkh using highway ops

libvips/resample/meson.build

@@ -8,6 +8,7 @@ resample_sources = files(
     'resize.c',
     'shrink.c',
     'shrinkh.c',
+    'shrinkh_hwy.cpp',
     'shrinkv.c',
     'shrinkv_hwy.cpp',
     'reduce.c',

libvips/resample/presample.h

@@ -78,6 +78,8 @@ void vips_reduceh_uchar_hwy(VipsPel *pout, VipsPel *pin,
 void vips_reducev_uchar_hwy(VipsPel *pout, VipsPel *pin,
 	int n, int ne, int lskip, const short *restrict k);
 
+void vips_shrinkh_uchar_hwy(VipsPel *pout, VipsPel *pin,
+	int width, int hshrink, int bands);
 void vips_shrinkv_uchar_hwy(VipsPel *pout, VipsPel *pin,
 	int ne, int vshrink, int lskip);
 

libvips/resample/shrinkh.c

@@ -55,6 +55,7 @@
 #include <math.h>
 
 #include <vips/vips.h>
+#include <vips/vector.h>
 #include <vips/debug.h>
 #include <vips/internal.h>
 
@@ -262,6 +263,73 @@ vips_shrinkh_gen(VipsRegion *out_region,
 	return 0;
 }
 
+#ifdef HAVE_HWY
+static int
+vips_shrinkh_uchar_vector_gen(VipsRegion *out_region,
+	void *seq, void *a, void *b, gboolean *stop)
+{
+	/* How do we chunk up the image? We don't want to prepare the whole of
+	 * the input region corresponding to *r since it could be huge.
+	 *
+	 * Reading a line at a time could cause a lot of overcomputation, depending
+	 * on what's upstream from us. In SMALLTILE, output scanlines could be
+	 * quite small.
+	 *
+	 * Use fatstrip height as a compromise.
+	 */
+	const int dy = vips__fatstrip_height;
+
+	VipsImage *in = (VipsImage *) a;
+	VipsShrinkh *shrink = (VipsShrinkh *) b;
+	VipsRegion *ir = (VipsRegion *) seq;
+	VipsRect *r = &out_region->valid;
+	const int bands = in->Bands;
+
+	int y, y1;
+
+#ifdef DEBUG
+	printf("vips_shrinkh_uchar_vector_gen: generating %d x %d at %d x %d\n",
+		r->width, r->height, r->left, r->top);
+#endif /*DEBUG*/
+
+	for (y = 0; y < r->height; y += dy) {
+		int chunk_height = VIPS_MIN(dy, r->height - y);
+
+		VipsRect s;
+
+		s.left = r->left * shrink->hshrink;
+		s.top = r->top + y;
+		s.width = r->width * shrink->hshrink;
+		s.height = chunk_height;
+#ifdef DEBUG
+		printf("vips_shrinkh_uchar_vector_gen: requesting %d lines from %d\n",
+			s.height, s.top);
+#endif /*DEBUG*/
+		if (vips_region_prepare(ir, &s))
+			return -1;
+
+		VIPS_GATE_START("vips_shrinkh_uchar_vector_gen: work");
+
+		// each output line
+		for (y1 = 0; y1 < chunk_height; y1++) {
+			// top of this line in the output
+			int top = r->top + y + y1;
+
+			VipsPel *q = VIPS_REGION_ADDR(out_region, r->left, top);
+			VipsPel *p = VIPS_REGION_ADDR(ir, s.left, top);
+
+			vips_shrinkh_uchar_hwy(q, p, r->width, shrink->hshrink, bands);
+		}
+
+		VIPS_GATE_STOP("vips_shrinkh_uchar_vector_gen: work");
+	}
+
+	VIPS_COUNT_PIXELS(out_region, "vips_shrinkh_uchar_vector_gen");
+
+	return 0;
+}
+#endif /*HAVE_HWY*/
+
 static int
 vips_shrinkh_build(VipsObject *object)
 {
@@ -272,6 +340,7 @@ vips_shrinkh_build(VipsObject *object)
 		vips_object_local_array(object, 2);
 
 	VipsImage *in;
+	VipsGenerateFn generate;
 
 	if (VIPS_OBJECT_CLASS(vips_shrinkh_parent_class)->build(object))
 		return -1;
@@ -298,6 +367,20 @@ vips_shrinkh_build(VipsObject *object)
 		return -1;
 	in = t[1];
 
+	/* For uchar input, try to make a vector path.
+	 */
+#ifdef HAVE_HWY
+	if (in->BandFmt == VIPS_FORMAT_UCHAR &&
+		vips_vector_isenabled()) {
+		generate = vips_shrinkh_uchar_vector_gen;
+		g_info("shrinkh: using vector path");
+	}
+	else
+#endif /*HAVE_HWY*/
+		/* Default to the C path.
+		 */
+		generate = vips_shrinkh_gen;
+
 	if (vips_image_pipelinev(resample->out,
 			VIPS_DEMAND_STYLE_THINSTRIP, in, NULL))
 		return -1;
@@ -324,7 +407,7 @@ vips_shrinkh_build(VipsObject *object)
 #endif /*DEBUG*/
 
 	if (vips_image_generate(resample->out,
-			vips_start_one, vips_shrinkh_gen, vips_stop_one,
+			vips_start_one, generate, vips_stop_one,
 			in, shrink))
 		return -1;
 

libvips/resample/shrinkh_hwy.cpp

@@ -0,0 +1,129 @@
+/* 15/11/24 kleisauke
+ * 	- from shrinkv_hwy.cpp
+ */
+
+/*
+
+	This file is part of VIPS.
+
+	VIPS 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 of the License, or
+	(at your option) any later version.
+
+	This program 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 this program; if not, write to the Free Software
+	Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+	02110-1301  USA
+
+ */
+
+/*
+
+	These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
+
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif /*HAVE_CONFIG_H*/
+#include <glib/gi18n-lib.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+
+#include <vips/vips.h>
+#include <vips/vector.h>
+#include <vips/debug.h>
+#include <vips/internal.h>
+
+#include "presample.h"
+
+#ifdef HAVE_HWY
+
+#undef HWY_TARGET_INCLUDE
+#define HWY_TARGET_INCLUDE "libvips/resample/shrinkh_hwy.cpp"
+#include <hwy/foreach_target.h>
+#include <hwy/highway.h>
+
+namespace HWY_NAMESPACE {
+
+using namespace hwy::HWY_NAMESPACE;
+
+using DU32 = ScalableTag<uint32_t>;
+constexpr Rebind<uint8_t, DU32> du8x32;
+constexpr DU32 du32;
+
+constexpr int64_t max_uint32 = 1LL << 32;
+constexpr int32_t max_bits = 1 << 8;
+
+HWY_ATTR void
+vips_shrinkh_uchar_hwy(VipsPel *pout, VipsPel *pin,
+	int32_t width, int32_t hshrink, int32_t bands)
+{
+#if HWY_TARGET != HWY_SCALAR
+	const auto multiplier = Set(du32, max_uint32 / (max_bits * hshrink));
+	const auto amend = Set(du32, hshrink / 2);
+
+	int32_t ix = 0;
+
+	for (int32_t x = 0; x < width; ++x) {
+		auto *HWY_RESTRICT p = (uint8_t *) pin + ix * bands;
+		auto *HWY_RESTRICT q = (uint8_t *) pout + x * bands;
+
+		auto sum0 = amend;
+
+		int32_t xx = 0;
+		for (; xx + 2 <= hshrink; xx += 2) {
+			auto pix0 = PromoteTo(du32, LoadU(du8x32, p));
+			p += bands;
+			auto pix1 = PromoteTo(du32, LoadU(du8x32, p));
+			p += bands;
+
+			pix0 = Add(pix0, pix1);
+			sum0 = Add(sum0, pix0);
+		}
+		for (; xx < hshrink; ++xx) {
+			auto pix0 = PromoteTo(du32, LoadU(du8x32, p));
+			p += bands;
+
+			sum0 = Add(sum0, pix0);
+		}
+
+		sum0 = Mul(sum0, multiplier);
+
+		/* The final 32->8 conversion.
+		 */
+		sum0 = ShiftRight<24>(sum0);
+
+		auto demoted = DemoteTo(du8x32, sum0);
+		StoreU(demoted, du8x32, q);
+
+		ix += hshrink;
+	}
+#endif
+}
+
+} /*namespace HWY_NAMESPACE*/
+
+#if HWY_ONCE
+HWY_EXPORT(vips_shrinkh_uchar_hwy);
+
+void
+vips_shrinkh_uchar_hwy(VipsPel *pout, VipsPel *pin,
+	int width, int hshrink, int bands)
+{
+	/* clang-format off */
+	HWY_DYNAMIC_DISPATCH(vips_shrinkh_uchar_hwy)(pout, pin,
+		width, hshrink, bands);
+	/* clang-format on */
+}
+#endif /*HWY_ONCE*/
+
+#endif /*HAVE_HWY*/