test: check correctness of 'bilinear_pad_repeat_get_scanline_bounds'

Individual correctness check for the new bilinear scaling related
supplementary function. This test program uses a bit wider range
of input arguments, not covered by other tests.

2 files changed, 95 insertions, 0 deletions

diff --git a/test/Makefile.am b/test/Makefile.am
index 057e9ced..9dc72199 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -13,6 +13,7 @@ TESTPROGRAMS =			\
 	trap-crasher		\
 	alpha-loop		\
 	scaling-crash-test	\
+	scaling-helpers-test	\
 	gradient-crash-test	\
 	alphamap		\
 	stress-test		\
@@ -33,6 +34,7 @@ alpha_loop_SOURCES = alpha-loop.c utils.c utils.h
 composite_SOURCES = composite.c utils.c utils.h
 gradient_crash_test_SOURCES = gradient-crash-test.c utils.c utils.h
 stress_test_SOURCES = stress-test.c utils.c utils.h
+scaling_helpers_test_SOURCES = scaling-helpers-test.c utils.c utils.h
 
 # Benchmarks
 
diff --git a/test/scaling-helpers-test.c b/test/scaling-helpers-test.c
new file mode 100644
index 00000000..c1861389
--- /dev/null
+++ b/test/scaling-helpers-test.c
@@ -0,0 +1,93 @@
+#include <config.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <assert.h>
+#include "utils.h"
+#include "pixman-fast-path.h"
+
+/* A trivial reference implementation for
+ * 'bilinear_pad_repeat_get_scanline_bounds'
+ */
+static void
+bilinear_pad_repeat_get_scanline_bounds_ref (int32_t        source_image_width,
+					     pixman_fixed_t vx_,
+					     pixman_fixed_t unit_x,
+					     int32_t *      left_pad,
+					     int32_t *      left_tz,
+					     int32_t *      width,
+					     int32_t *      right_tz,
+					     int32_t *      right_pad)
+{
+    int w = *width;
+    *left_pad = 0;
+    *left_tz = 0;
+    *width = 0;
+    *right_tz = 0;
+    *right_pad = 0;
+    int64_t vx = vx_;
+    while (--w >= 0)
+    {
+	if (vx < 0)
+	{
+	    if (vx + pixman_fixed_1 < 0)
+		*left_pad += 1;
+	    else
+		*left_tz += 1;
+	}
+	else if (vx + pixman_fixed_1 >= pixman_int_to_fixed (source_image_width))
+	{
+	    if (vx >= pixman_int_to_fixed (source_image_width))
+		*right_pad += 1;
+	    else
+		*right_tz += 1;
+	}
+	else
+	{
+	    *width += 1;
+	}
+	vx += unit_x;
+    }
+}
+
+int
+main (void)
+{
+    int i;
+    for (i = 0; i < 10000; i++)
+    {
+	int32_t left_pad1, left_tz1, width1, right_tz1, right_pad1;
+	int32_t left_pad2, left_tz2, width2, right_tz2, right_pad2;
+	pixman_fixed_t vx = lcg_rand_N(10000 << 16) - (3000 << 16);
+	int32_t width = lcg_rand_N(10000);
+	int32_t source_image_width = lcg_rand_N(10000) + 1;
+	pixman_fixed_t unit_x = lcg_rand_N(10 << 16) + 1;
+	width1 = width2 = width;
+
+	bilinear_pad_repeat_get_scanline_bounds_ref (source_image_width,
+						     vx,
+						     unit_x,
+						     &left_pad1,
+						     &left_tz1,
+						     &width1,
+						     &right_tz1,
+						     &right_pad1);
+
+	bilinear_pad_repeat_get_scanline_bounds (source_image_width,
+						 vx,
+						 unit_x,
+						 &left_pad2,
+						 &left_tz2,
+						 &width2,
+						 &right_tz2,
+						 &right_pad2);
+
+	assert (left_pad1 == left_pad2);
+	assert (left_tz1 == left_tz2);
+	assert (width1 == width2);
+	assert (right_tz1 == right_tz2);
+	assert (right_pad1 == right_pad2);
+    }
+
+    return 0;
+}