This also avoids the floating point conversion steps and just
uses pure integer arithmetic.
Since the G2D hardware scaling approach is a bit unintuitive,
document it in the function as well.
v2: Explicitly mention the normalization constant.
v3: Use common commenting style as pointed out by
Emil Velikov <emil.l.velikov at gmail.com>.
Signed-off-by: Tobias Jakobi <tjakobi@xxxxxxxxxxxxxxxxxxxxx>
---
exynos/exynos_fimg2d.c | 22 +++++++++++++++++-----
exynos/fimg2d.h | 2 --
2 files changed, 17 insertions(+), 7 deletions(-)
diff --git a/exynos/exynos_fimg2d.c b/exynos/exynos_fimg2d.c
index ce1ba1e..9c66c3a 100644
--- a/exynos/exynos_fimg2d.c
+++ b/exynos/exynos_fimg2d.c
@@ -41,6 +41,18 @@
#define MIN(a, b) ((a) < (b) ? (a) : (b))
+static unsigned int g2d_get_scaling(unsigned int src, unsigned int dst)
+{
+ /*
+ * The G2D hw scaling factor is a normalized inverse of the scaling factor.
+ * For example: When source width is 100 and destination width is 200
+ * (scaling of 2x), then the hw factor is NC * 100 / 200.
+ * The normalization factor (NC) is 2^16 = 0x10000.
+ */
+
+ return ((src << 16) / dst);
+}
+
static unsigned int g2d_get_blend_op(enum e_g2d_op op)
{
union g2d_blend_func_val val;
@@ -428,7 +440,7 @@ g2d_copy_with_scale(struct g2d_context *ctx, struct g2d_image *src,
union g2d_rop4_val rop4;
union g2d_point_val pt;
unsigned int scale;
- double scale_x = 0.0f, scale_y = 0.0f;
+ unsigned int scale_x, scale_y;
g2d_add_cmd(ctx, DST_SELECT_REG, G2D_SELECT_MODE_BGCOLOR);
g2d_add_cmd(ctx, DST_COLOR_MODE_REG, dst->color_mode);
@@ -454,8 +466,8 @@ g2d_copy_with_scale(struct g2d_context *ctx, struct g2d_image *src,
scale = 0;
else {
scale = 1;
- scale_x = (double)src_w / (double)dst_w;
- scale_y = (double)src_h / (double)dst_h;
+ scale_x = g2d_get_scaling(src_w, dst_w);
+ scale_y = g2d_get_scaling(src_h, dst_h);
}
if (src_x + src_w > src->width)
@@ -487,8 +499,8 @@ g2d_copy_with_scale(struct g2d_context *ctx, struct g2d_image *src,
if (scale) {
g2d_add_cmd(ctx, SRC_SCALE_CTRL_REG, G2D_SCALE_MODE_BILINEAR);
- g2d_add_cmd(ctx, SRC_XSCALE_REG, G2D_DOUBLE_TO_FIXED(scale_x));
- g2d_add_cmd(ctx, SRC_YSCALE_REG, G2D_DOUBLE_TO_FIXED(scale_y));
+ g2d_add_cmd(ctx, SRC_XSCALE_REG, scale_x);
+ g2d_add_cmd(ctx, SRC_YSCALE_REG, scale_y);
}
pt.val = 0;
diff --git a/exynos/fimg2d.h b/exynos/fimg2d.h
index 4785e2f..8e0321c 100644
--- a/exynos/fimg2d.h
+++ b/exynos/fimg2d.h
@@ -25,8 +25,6 @@
#define G2D_MAX_CMD_LIST_NR 64
#define G2D_PLANE_MAX_NR 2
-#define G2D_DOUBLE_TO_FIXED(d) ((unsigned int)((d) * 65536.0))
-
enum e_g2d_color_mode {
/* COLOR FORMAT */
G2D_COLOR_FMT_XRGB8888,
--
2.0.5
--
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