pixman-access.c: Add floating point accessor functions

Three new function pointer fields are added to bits_image_t:

      fetch_scanline_float
      fetch_pixel_float
      store_scanline_float

similar to the existing 32 and 64 bit accessors. The fetcher_info_t
struct in pixman_access similarly gets a new get_scanline_float field.

For most formats, the new get_scanline_float field is set to a new
function fetch_scanline_generic_float() that first calls the 32 bit
fetcher uses the 32 bit scanline fetcher and then expands these pixels
to floating point.

For the 10 bpc formats, new floating point accessors are added that
use pixman_unorm_to_float() and pixman_float_to_unorm() to convert
back and forth.

The PIXMAN_a8r8g8b8_sRGB format is handled with a 256-entry table that
maps 8 bit sRGB channels to linear single precision floating point
numbers. The sRGB->linear direction can then be done with a simple
table lookup.

The other direction is currently done with 4096-entry table which
works fine for 16 bit integers, but not so great for floating
point. So instead this patch uses a binary search in the sRGB->linear
table. The existing 32 bit accessors for the sRGB format are also
converted to use this method.

3 files changed, 624 insertions, 43 deletions

diff --git a/pixman/pixman-access.c b/pixman/pixman-access.c
index 9feafc4..1eef621 100644
--- a/pixman/pixman-access.c
+++ b/pixman/pixman-access.c
@@ -31,6 +31,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <assert.h>
+#include <math.h>
 
 #include "pixman-accessor.h"
 #include "pixman-private.h"
@@ -635,6 +636,231 @@ fetch_scanline_x2b10g10r10 (pixman_image_t *image,
     }
 }
 
+/* Table mapping sRGB-encoded 8 bit numbers to linearly encoded
+ * floating point numbers. We assume that single precision
+ * floating point follows the IEEE 754 format.
+ */
+static const uint32_t to_linear_u[256] =
+{
+    0x00000000, 0x399f22b4, 0x3a1f22b4, 0x3a6eb40e, 0x3a9f22b4, 0x3ac6eb61,
+    0x3aeeb40e, 0x3b0b3e5d, 0x3b1f22b4, 0x3b33070b, 0x3b46eb61, 0x3b5b518a,
+    0x3b70f18a, 0x3b83e1c5, 0x3b8fe614, 0x3b9c87fb, 0x3ba9c9b5, 0x3bb7ad6d,
+    0x3bc63547, 0x3bd5635f, 0x3be539bd, 0x3bf5ba70, 0x3c0373b5, 0x3c0c6152,
+    0x3c15a703, 0x3c1f45bc, 0x3c293e68, 0x3c3391f4, 0x3c3e4149, 0x3c494d43,
+    0x3c54b6c7, 0x3c607eb1, 0x3c6ca5df, 0x3c792d22, 0x3c830aa8, 0x3c89af9e,
+    0x3c9085db, 0x3c978dc5, 0x3c9ec7c0, 0x3ca63432, 0x3cadd37d, 0x3cb5a601,
+    0x3cbdac20, 0x3cc5e639, 0x3cce54ab, 0x3cd6f7d2, 0x3cdfd00e, 0x3ce8ddb9,
+    0x3cf2212c, 0x3cfb9ac1, 0x3d02a569, 0x3d0798dc, 0x3d0ca7e4, 0x3d11d2ae,
+    0x3d171963, 0x3d1c7c2e, 0x3d21fb3a, 0x3d2796af, 0x3d2d4ebb, 0x3d332380,
+    0x3d39152b, 0x3d3f23e3, 0x3d454fd0, 0x3d4b991c, 0x3d51ffeb, 0x3d588466,
+    0x3d5f26b7, 0x3d65e6fe, 0x3d6cc564, 0x3d73c210, 0x3d7add25, 0x3d810b65,
+    0x3d84b793, 0x3d88732e, 0x3d8c3e48, 0x3d9018f4, 0x3d940343, 0x3d97fd48,
+    0x3d9c0714, 0x3da020b9, 0x3da44a48, 0x3da883d6, 0x3daccd70, 0x3db12728,
+    0x3db59110, 0x3dba0b38, 0x3dbe95b2, 0x3dc3308f, 0x3dc7dbe0, 0x3dcc97b4,
+    0x3dd1641c, 0x3dd6412a, 0x3ddb2eec, 0x3de02d75, 0x3de53cd3, 0x3dea5d16,
+    0x3def8e52, 0x3df4d091, 0x3dfa23e5, 0x3dff885e, 0x3e027f06, 0x3e05427f,
+    0x3e080ea2, 0x3e0ae376, 0x3e0dc104, 0x3e10a752, 0x3e139669, 0x3e168e50,
+    0x3e198f0e, 0x3e1c98ab, 0x3e1fab2e, 0x3e22c6a0, 0x3e25eb08, 0x3e29186a,
+    0x3e2c4ed0, 0x3e2f8e42, 0x3e32d6c4, 0x3e362861, 0x3e39831e, 0x3e3ce702,
+    0x3e405416, 0x3e43ca5e, 0x3e4749e4, 0x3e4ad2ae, 0x3e4e64c2, 0x3e520027,
+    0x3e55a4e6, 0x3e595303, 0x3e5d0a8a, 0x3e60cb7c, 0x3e6495e0, 0x3e6869bf,
+    0x3e6c4720, 0x3e702e08, 0x3e741e7f, 0x3e78188c, 0x3e7c1c34, 0x3e8014c0,
+    0x3e822039, 0x3e84308b, 0x3e8645b8, 0x3e885fc3, 0x3e8a7eb0, 0x3e8ca281,
+    0x3e8ecb3a, 0x3e90f8df, 0x3e932b72, 0x3e9562f6, 0x3e979f6f, 0x3e99e0e0,
+    0x3e9c274e, 0x3e9e72b8, 0x3ea0c322, 0x3ea31892, 0x3ea57308, 0x3ea7d28a,
+    0x3eaa3718, 0x3eaca0b7, 0x3eaf0f69, 0x3eb18332, 0x3eb3fc16, 0x3eb67a15,
+    0x3eb8fd34, 0x3ebb8576, 0x3ebe12de, 0x3ec0a56e, 0x3ec33d2a, 0x3ec5da14,
+    0x3ec87c30, 0x3ecb2380, 0x3ecdd008, 0x3ed081ca, 0x3ed338c9, 0x3ed5f508,
+    0x3ed8b68a, 0x3edb7d52, 0x3ede4962, 0x3ee11abe, 0x3ee3f168, 0x3ee6cd64,
+    0x3ee9aeb6, 0x3eec955d, 0x3eef815d, 0x3ef272ba, 0x3ef56976, 0x3ef86594,
+    0x3efb6717, 0x3efe6e02, 0x3f00bd2b, 0x3f02460c, 0x3f03d1a5, 0x3f055ff8,
+    0x3f06f105, 0x3f0884ce, 0x3f0a1b54, 0x3f0bb499, 0x3f0d509f, 0x3f0eef65,
+    0x3f1090ef, 0x3f12353c, 0x3f13dc50, 0x3f15862a, 0x3f1732cc, 0x3f18e237,
+    0x3f1a946d, 0x3f1c4970, 0x3f1e013f, 0x3f1fbbde, 0x3f21794c, 0x3f23398c,
+    0x3f24fca0, 0x3f26c286, 0x3f288b42, 0x3f2a56d3, 0x3f2c253d, 0x3f2df680,
+    0x3f2fca9d, 0x3f31a195, 0x3f337b6a, 0x3f35581e, 0x3f3737b1, 0x3f391a24,
+    0x3f3aff7a, 0x3f3ce7b2, 0x3f3ed2d0, 0x3f40c0d2, 0x3f42b1bc, 0x3f44a58e,
+    0x3f469c49, 0x3f4895ee, 0x3f4a9280, 0x3f4c91ff, 0x3f4e946c, 0x3f5099c8,
+    0x3f52a216, 0x3f54ad55, 0x3f56bb88, 0x3f58ccae, 0x3f5ae0cb, 0x3f5cf7de,
+    0x3f5f11ec, 0x3f612ef0, 0x3f634eef, 0x3f6571ea, 0x3f6797e1, 0x3f69c0d6,
+    0x3f6beccb, 0x3f6e1bc0, 0x3f704db6, 0x3f7282af, 0x3f74baac, 0x3f76f5ae,
+    0x3f7933b6, 0x3f7b74c6, 0x3f7db8de, 0x3f800000
+};
+
+static const float * const to_linear = (const float *)to_linear_u;
+
+static uint8_t
+to_srgb (float f)
+{
+    uint8_t low = 0;
+    uint8_t high = 255;
+
+    while (high - low > 1)
+    {
+	uint8_t mid = (low + high) / 2;
+
+	if (to_linear[mid] > f)
+	    high = mid;
+	else
+	    low = mid;
+    }
+
+    if (to_linear[high] - f < f - to_linear[low])
+	return high;
+    else
+	return low;
+}
+
+static void
+fetch_scanline_a8r8g8b8_sRGB_float (pixman_image_t *image,
+				    int             x,
+				    int             y,
+				    int             width,
+				    uint32_t *      b,
+				    const uint32_t *mask)
+{
+    const uint32_t *bits = image->bits.bits + y * image->bits.rowstride;
+    const uint32_t *pixel = bits + x;
+    const uint32_t *end = pixel + width;
+    argb_t *buffer = (argb_t *)b;
+
+    while (pixel < end)
+    {
+	uint32_t p = READ (image, pixel++);
+	argb_t *argb = buffer;
+
+	argb->a = pixman_unorm_to_float ((p >> 24) & 0xff, 8);
+
+	argb->r = to_linear [(p >> 16) & 0xff];
+	argb->g = to_linear [(p >>  8) & 0xff];
+	argb->b = to_linear [(p >>  0) & 0xff];
+
+	buffer++;
+    }
+}
+
+/* Expects a float buffer */
+static void
+fetch_scanline_a2r10g10b10_float (pixman_image_t *image,
+				  int             x,
+				  int             y,
+				  int             width,
+				  uint32_t *      b,
+				  const uint32_t *mask)
+{
+    const uint32_t *bits = image->bits.bits + y * image->bits.rowstride;
+    const uint32_t *pixel = bits + x;
+    const uint32_t *end = pixel + width;
+    argb_t *buffer = (argb_t *)b;
+
+    while (pixel < end)
+    {
+	uint32_t p = READ (image, pixel++);
+	uint64_t a = p >> 30;
+	uint64_t r = (p >> 20) & 0x3ff;
+	uint64_t g = (p >> 10) & 0x3ff;
+	uint64_t b = p & 0x3ff;
+
+	buffer->a = pixman_unorm_to_float (a, 2);
+	buffer->r = pixman_unorm_to_float (r, 10);
+	buffer->g = pixman_unorm_to_float (g, 10);
+	buffer->b = pixman_unorm_to_float (b, 10);
+
+	buffer++;
+    }
+}
+
+/* Expects a float buffer */
+static void
+fetch_scanline_x2r10g10b10_float (pixman_image_t *image,
+				  int             x,
+				  int             y,
+				  int             width,
+				  uint32_t *      b,
+				  const uint32_t *mask)
+{
+    const uint32_t *bits = image->bits.bits + y * image->bits.rowstride;
+    const uint32_t *pixel = (uint32_t *)bits + x;
+    const uint32_t *end = pixel + width;
+    argb_t *buffer = (argb_t *)b;
+
+    while (pixel < end)
+    {
+	uint32_t p = READ (image, pixel++);
+	uint64_t r = (p >> 20) & 0x3ff;
+	uint64_t g = (p >> 10) & 0x3ff;
+	uint64_t b = p & 0x3ff;
+
+	buffer->a = 1.0;
+	buffer->r = pixman_unorm_to_float (r, 10);
+	buffer->g = pixman_unorm_to_float (g, 10);
+	buffer->b = pixman_unorm_to_float (b, 10);
+
+	buffer++;
+    }
+}
+
+/* Expects a float buffer */
+static void
+fetch_scanline_a2b10g10r10_float (pixman_image_t *image,
+				  int             x,
+				  int             y,
+				  int             width,
+				  uint32_t *      b,
+				  const uint32_t *mask)
+{
+    const uint32_t *bits = image->bits.bits + y * image->bits.rowstride;
+    const uint32_t *pixel = bits + x;
+    const uint32_t *end = pixel + width;
+    argb_t *buffer = (argb_t *)b;
+
+    while (pixel < end)
+    {
+	uint32_t p = READ (image, pixel++);
+	uint64_t a = p >> 30;
+	uint64_t b = (p >> 20) & 0x3ff;
+	uint64_t g = (p >> 10) & 0x3ff;
+	uint64_t r = p & 0x3ff;
+
+	buffer->a = pixman_unorm_to_float (a, 2);
+	buffer->r = pixman_unorm_to_float (r, 10);
+	buffer->g = pixman_unorm_to_float (g, 10);
+	buffer->b = pixman_unorm_to_float (b, 10);
+
+	buffer++;
+    }
+}
+
+/* Expects a float buffer */
+static void
+fetch_scanline_x2b10g10r10_float (pixman_image_t *image,
+				  int             x,
+				  int             y,
+				  int             width,
+				  uint32_t *      b,
+				  const uint32_t *mask)
+{
+    const uint32_t *bits = image->bits.bits + y * image->bits.rowstride;
+    const uint32_t *pixel = (uint32_t *)bits + x;
+    const uint32_t *end = pixel + width;
+    argb_t *buffer = (argb_t *)b;
+
+    while (pixel < end)
+    {
+	uint32_t p = READ (image, pixel++);
+	uint64_t b = (p >> 20) & 0x3ff;
+	uint64_t g = (p >> 10) & 0x3ff;
+	uint64_t r = p & 0x3ff;
+
+	buffer->a = 1.0;
+	buffer->r = pixman_unorm_to_float (r, 10);
+	buffer->g = pixman_unorm_to_float (g, 10);
+	buffer->b = pixman_unorm_to_float (b, 10);
+
+	buffer++;
+    }
+}
+
 static void
 fetch_scanline_yuy2 (pixman_image_t *image,
                      int             x,
@@ -796,6 +1022,106 @@ fetch_pixel_x2b10g10r10 (bits_image_t *image,
     return 0xffffULL << 48 | r << 32 | g << 16 | b;
 }
 
+static argb_t
+fetch_pixel_x2r10g10b10_float (bits_image_t *image,
+			       int	   offset,
+			       int           line)
+{
+    uint32_t *bits = image->bits + line * image->rowstride;
+    uint32_t p = READ (image, bits + offset);
+    uint64_t r = (p >> 20) & 0x3ff;
+    uint64_t g = (p >> 10) & 0x3ff;
+    uint64_t b = p & 0x3ff;
+    argb_t argb;
+
+    argb.a = 1.0;
+    argb.r = pixman_unorm_to_float (r, 10);
+    argb.g = pixman_unorm_to_float (g, 10);
+    argb.b = pixman_unorm_to_float (b, 10);
+
+    return argb;
+}
+
+static argb_t
+fetch_pixel_a2r10g10b10_float (bits_image_t *image,
+			       int	     offset,
+			       int           line)
+{
+    uint32_t *bits = image->bits + line * image->rowstride;
+    uint32_t p = READ (image, bits + offset);
+    uint64_t a = p >> 30;
+    uint64_t r = (p >> 20) & 0x3ff;
+    uint64_t g = (p >> 10) & 0x3ff;
+    uint64_t b = p & 0x3ff;
+    argb_t argb;
+
+    argb.a = pixman_unorm_to_float (a, 2);
+    argb.r = pixman_unorm_to_float (r, 10);
+    argb.g = pixman_unorm_to_float (g, 10);
+    argb.b = pixman_unorm_to_float (b, 10);
+
+    return argb;
+}
+
+static argb_t
+fetch_pixel_a2b10g10r10_float (bits_image_t *image,
+			       int           offset,
+			       int           line)
+{
+    uint32_t *bits = image->bits + line * image->rowstride;
+    uint32_t p = READ (image, bits + offset);
+    uint64_t a = p >> 30;
+    uint64_t b = (p >> 20) & 0x3ff;
+    uint64_t g = (p >> 10) & 0x3ff;
+    uint64_t r = p & 0x3ff;
+    argb_t argb;
+
+    argb.a = pixman_unorm_to_float (a, 2);
+    argb.r = pixman_unorm_to_float (r, 10);
+    argb.g = pixman_unorm_to_float (g, 10);
+    argb.b = pixman_unorm_to_float (b, 10);
+
+    return argb;
+}
+
+static argb_t
+fetch_pixel_x2b10g10r10_float (bits_image_t *image,
+			       int           offset,
+			       int           line)
+{
+    uint32_t *bits = image->bits + line * image->rowstride;
+    uint32_t p = READ (image, bits + offset);
+    uint64_t b = (p >> 20) & 0x3ff;
+    uint64_t g = (p >> 10) & 0x3ff;
+    uint64_t r = p & 0x3ff;
+    argb_t argb;
+
+    argb.a = 1.0;
+    argb.r = pixman_unorm_to_float (r, 10);
+    argb.g = pixman_unorm_to_float (g, 10);
+    argb.b = pixman_unorm_to_float (b, 10);
+
+    return argb;
+}
+
+static argb_t
+fetch_pixel_a8r8g8b8_sRGB_float (bits_image_t *image,
+				 int	       offset,
+				 int           line)
+{
+    uint32_t *bits = image->bits + line * image->rowstride;
+    uint32_t p = READ (image, bits + offset);
+    argb_t argb;
+
+    argb.a = pixman_unorm_to_float ((p >> 24) & 0xff, 8);
+
+    argb.r = to_linear [(p >> 16) & 0xff];
+    argb.g = to_linear [(p >>  8) & 0xff];
+    argb.b = to_linear [(p >>  0) & 0xff];
+
+    return argb;
+}
+
 static uint32_t
 fetch_pixel_yuy2 (bits_image_t *image,
 		  int           offset,
@@ -939,6 +1265,135 @@ store_scanline_x2b10g10r10 (bits_image_t *  image,
     }
 }
 
+
+static void
+store_scanline_a2r10g10b10_float (bits_image_t *  image,
+				  int             x,
+				  int             y,
+				  int             width,
+				  const uint32_t *v)
+{
+    uint32_t *bits = image->bits + image->rowstride * y;
+    uint32_t *pixel = bits + x;
+    argb_t *values = (argb_t *)v;
+    int i;
+
+    for (i = 0; i < width; ++i)
+    {
+	uint16_t a, r, g, b;
+
+	a = pixman_float_to_unorm (values[i].a, 2);
+	r = pixman_float_to_unorm (values[i].r, 10);
+	g = pixman_float_to_unorm (values[i].g, 10);
+	b = pixman_float_to_unorm (values[i].b, 10);
+
+	WRITE (image, pixel++,
+	       (a << 30) | (r << 20) | (g << 10) | b);
+    }
+}
+
+static void
+store_scanline_x2r10g10b10_float (bits_image_t *  image,
+				  int             x,
+				  int             y,
+				  int             width,
+				  const uint32_t *v)
+{
+    uint32_t *bits = image->bits + image->rowstride * y;
+    uint32_t *pixel = bits + x;
+    argb_t *values = (argb_t *)v;
+    int i;
+
+    for (i = 0; i < width; ++i)
+    {
+	uint16_t r, g, b;
+
+	r = pixman_float_to_unorm (values[i].r, 10);
+	g = pixman_float_to_unorm (values[i].g, 10);
+	b = pixman_float_to_unorm (values[i].b, 10);
+
+	WRITE (image, pixel++,
+	       (r << 20) | (g << 10) | b);
+    }
+}
+
+static void
+store_scanline_a2b10g10r10_float (bits_image_t *  image,
+				  int             x,
+				  int             y,
+				  int             width,
+				  const uint32_t *v)
+{
+    uint32_t *bits = image->bits + image->rowstride * y;
+    uint32_t *pixel = bits + x;
+    argb_t *values = (argb_t *)v;
+    int i;
+
+    for (i = 0; i < width; ++i)
+    {
+	uint16_t a, r, g, b;
+
+	a = pixman_float_to_unorm (values[i].a, 2);
+	r = pixman_float_to_unorm (values[i].r, 10);
+	g = pixman_float_to_unorm (values[i].g, 10);
+	b = pixman_float_to_unorm (values[i].b, 10);
+
+	WRITE (image, pixel++,
+	       (a << 30) | (b << 20) | (g << 10) | r);
+    }
+}
+
+static void
+store_scanline_x2b10g10r10_float (bits_image_t *  image,
+				  int             x,
+				  int             y,
+				  int             width,
+				  const uint32_t *v)
+{
+    uint32_t *bits = image->bits + image->rowstride * y;
+    uint32_t *pixel = bits + x;
+    argb_t *values = (argb_t *)v;
+    int i;
+
+    for (i = 0; i < width; ++i)
+    {
+	uint16_t r, g, b;
+
+	r = pixman_float_to_unorm (values[i].r, 10);
+	g = pixman_float_to_unorm (values[i].g, 10);
+	b = pixman_float_to_unorm (values[i].b, 10);
+
+	WRITE (image, pixel++,
+	       (b << 20) | (g << 10) | r);
+    }
+}
+
+static void
+store_scanline_a8r8g8b8_sRGB_float (bits_image_t *  image,
+				    int             x,
+				    int             y,
+				    int             width,
+				    const uint32_t *v)
+{
+    uint32_t *bits = image->bits + image->rowstride * y;
+    uint32_t *pixel = bits + x;
+    argb_t *values = (argb_t *)v;
+    int i;
+
+    for (i = 0; i < width; ++i)
+    {
+	uint8_t a, r, g, b;
+
+	a = pixman_float_to_unorm (values[i].a, 8);
+	r = to_srgb (values[i].r);
+	g = to_srgb (values[i].g);
+	b = to_srgb (values[i].b);
+
+	WRITE (image, pixel++,
+	       (a << 24) | (r << 16) | (g << 8) | b);
+    }
+}
+
 /*
  * Contracts a 64bpp image to 32bpp and then stores it using a regular 32-bit
  * store proc. Despite the type, this function expects a uint64_t buffer.
@@ -968,6 +1423,36 @@ store_scanline_generic_64 (bits_image_t *  image,
     free (argb8_pixels);
 }
 
+/*
+ * Contracts a floating point image to 32bpp and then stores it using a
+ * regular 32-bit store proc. Despite the type, this function expects an
+ * argb_t buffer.
+ */
+static void
+store_scanline_generic_float (bits_image_t *  image,
+			      int             x,
+			      int             y,
+			      int             width,
+			      const uint32_t *values)
+{
+    uint32_t *argb8_pixels;
+
+    assert (image->common.type == BITS);
+
+    argb8_pixels = pixman_malloc_ab (width, sizeof(uint32_t));
+    if (!argb8_pixels)
+	return;
+
+    /* Contract the scanline.  We could do this in place if values weren't
+     * const.
+     */
+    pixman_contract_from_float (argb8_pixels, (argb_t *)values, width);
+
+    image->store_scanline_32 (image, x, y, width, argb8_pixels);
+
+    free (argb8_pixels);
+}
+
 /* Despite the type, this function expects both buffer
  * and mask to be uint64_t
  */
@@ -1001,6 +1486,19 @@ fetch_scanline_generic_64 (pixman_image_t *image,
     pixman_expand ((uint64_t *)buffer, buffer, format, width);
 }
 
+static void
+fetch_scanline_generic_float (pixman_image_t *image,
+			      int	      x,
+			      int	      y,
+			      int	      width,
+			      uint32_t *      buffer,
+			      const uint32_t *mask)
+{
+    image->bits.fetch_scanline_32 (image, x, y, width, buffer, NULL);
+
+    pixman_expand_to_float ((argb_t *)buffer, buffer, image->bits.format, width);
+}
+
 /* Despite the type, this function expects a uint64_t *buffer */
 static uint64_t
 fetch_pixel_generic_64 (bits_image_t *image,
@@ -1046,11 +1544,20 @@ fetch_scanline_a8r8g8b8_32_sRGB (pixman_image_t *image,
     
     while (pixel < end)
     {
+	uint8_t a, r, g, b;
+
 	tmp = READ (image, pixel++);
-	*buffer++ =                 (tmp >> 24)               << 24
-		  | (srgb_to_linear[(tmp >> 16) & 0xff] >> 8) << 16
-		  | (srgb_to_linear[(tmp >>  8) & 0xff] >> 8) <<  8
-		  | (srgb_to_linear[(tmp >>  0) & 0xff] >> 8) <<  0;
+
+	a = (tmp >> 24) & 0xff;
+	r = (tmp >> 16) & 0xff;
+	g = (tmp >> 8) & 0xff;
+	b = (tmp >> 0) & 0xff;
+
+	r = to_linear[r] * 255.0f + 0.5f;
+	g = to_linear[g] * 255.0f + 0.5f;
+	b = to_linear[b] * 255.0f + 0.5f;
+
+	*buffer++ = (a << 24) | (r << 16) | (g << 8) | (b << 0);
     }
 }
 
@@ -1085,10 +1592,18 @@ fetch_pixel_a8r8g8b8_32_sRGB (bits_image_t *image,
 {
     uint32_t *bits = image->bits + line * image->rowstride;
     uint32_t tmp = READ (image, bits + offset);
-    return                 (tmp >> 24)               << 24
-	 | (srgb_to_linear[(tmp >> 16) & 0xff] >> 8) << 16
-	 | (srgb_to_linear[(tmp >>  8) & 0xff] >> 8) <<  8
-	 | (srgb_to_linear[(tmp >>  0) & 0xff] >> 8) <<  0;
+    uint8_t a, r, g, b;
+
+    a = (tmp >> 24) & 0xff;
+    r = (tmp >> 16) & 0xff;
+    g = (tmp >> 8) & 0xff;
+    b = (tmp >> 0) & 0xff;
+
+    r = to_linear[r] * 255.0f + 0.5f;
+    g = to_linear[g] * 255.0f + 0.5f;
+    b = to_linear[b] * 255.0f + 0.5f;
+
+    return (a << 24) | (r << 16) | (g << 8) | (b << 0);
 }
 
 static uint64_t
@@ -1119,12 +1634,20 @@ store_scanline_a8r8g8b8_32_sRGB (bits_image_t   *image,
     
     for (i = 0; i < width; ++i)
     {
+	uint8_t a, r, g, b;
+
 	tmp = values[i];
-	WRITE (image, pixel++,
-		  ((uint32_t)     (tmp >> 24     )          << 24)
-		| (linear_to_srgb[(tmp >> 16 << 4) & 0xfff] << 16)
-		| (linear_to_srgb[(tmp >>  8 << 4) & 0xfff] <<  8)
-		| (linear_to_srgb[(tmp >>  0 << 4) & 0xfff] <<  0));
+
+	a = (tmp >> 24) & 0xff;
+	r = (tmp >> 16) & 0xff;
+	g = (tmp >> 8) & 0xff;
+	b = (tmp >> 0) & 0xff;
+
+	r = to_srgb (r * (1/255.0f));
+	g = to_srgb (g * (1/255.0f));
+	b = to_srgb (b * (1/255.0f));
+	
+	WRITE (image, pixel++, a | (r << 16) | (g << 8) | (b << 0));
     }
 }
 
@@ -1152,6 +1675,19 @@ store_scanline_a8r8g8b8_64_sRGB (bits_image_t  *image,
     }
 }
 
+static argb_t
+fetch_pixel_generic_float (bits_image_t *image,
+			   int		 offset,
+			   int           line)
+{
+    uint32_t pixel32 = image->fetch_pixel_32 (image, offset, line);
+    argb_t f;
+
+    pixman_expand_to_float (&f, &pixel32, image->format, 1);
+
+    return f;
+}
+
 /*
  * XXX: The transformed fetch path only works at 32-bpp so far.  When all
  * paths have wide versions, this can be removed.
@@ -1176,10 +1712,13 @@ typedef struct
     pixman_format_code_t	format;
     fetch_scanline_t		fetch_scanline_32;
     fetch_scanline_t		fetch_scanline_64;
+    fetch_scanline_t		fetch_scanline_float;
     fetch_pixel_32_t		fetch_pixel_32;
     fetch_pixel_64_t		fetch_pixel_64;
+    fetch_pixel_float_t		fetch_pixel_float;
     store_scanline_t		store_scanline_32;
     store_scanline_t		store_scanline_64;
+    store_scanline_t		store_scanline_float;
 } format_info_t;
 
 #define FORMAT_INFO(format) 						\
@@ -1187,8 +1726,13 @@ typedef struct
 	PIXMAN_ ## format,						\
 	    fetch_scanline_ ## format,					\
 	    fetch_scanline_generic_64,					\
-	    fetch_pixel_ ## format, fetch_pixel_generic_64,		\
-	    store_scanline_ ## format, store_scanline_generic_64	\
+	    fetch_scanline_generic_float,				\
+	    fetch_pixel_ ## format,					\
+	    fetch_pixel_generic_64,					\
+	    fetch_pixel_generic_float,					\
+	    store_scanline_ ## format,					\
+	    store_scanline_generic_64,					\
+	    store_scanline_generic_float				\
     }
 
 static const format_info_t accessors[] =
@@ -1206,10 +1750,10 @@ static const format_info_t accessors[] =
 
 /* sRGB formats */
   { PIXMAN_a8r8g8b8_sRGB,
-    fetch_scanline_a8r8g8b8_32_sRGB,
-    fetch_scanline_a8r8g8b8_64_sRGB,
-    fetch_pixel_a8r8g8b8_32_sRGB, fetch_pixel_a8r8g8b8_64_sRGB,
-    store_scanline_a8r8g8b8_32_sRGB, store_scanline_a8r8g8b8_64_sRGB },
+    fetch_scanline_a8r8g8b8_32_sRGB, fetch_scanline_a8r8g8b8_64_sRGB, fetch_scanline_a8r8g8b8_sRGB_float,
+    fetch_pixel_a8r8g8b8_32_sRGB, fetch_pixel_a8r8g8b8_64_sRGB, fetch_pixel_a8r8g8b8_sRGB_float,
+    store_scanline_a8r8g8b8_32_sRGB, store_scanline_a8r8g8b8_64_sRGB, store_scanline_a8r8g8b8_sRGB_float,
+  },
 
 /* 24bpp formats */
     FORMAT_INFO (r8g8b8),
@@ -1269,34 +1813,34 @@ static const format_info_t accessors[] =
 /* Wide formats */
     
     { PIXMAN_a2r10g10b10,
-      NULL, fetch_scanline_a2r10g10b10,
-      fetch_pixel_generic_lossy_32, fetch_pixel_a2r10g10b10,
-      NULL, store_scanline_a2r10g10b10 },
+      NULL, fetch_scanline_a2r10g10b10, fetch_scanline_a2r10g10b10_float,
+      fetch_pixel_generic_lossy_32, fetch_pixel_a2r10g10b10, fetch_pixel_a2r10g10b10_float,
+      NULL, store_scanline_a2r10g10b10, store_scanline_a2r10g10b10_float },
     
     { PIXMAN_x2r10g10b10,
-      NULL, fetch_scanline_x2r10g10b10,
-      fetch_pixel_generic_lossy_32, fetch_pixel_x2r10g10b10,
-      NULL, store_scanline_x2r10g10b10 },
+      NULL, fetch_scanline_x2r10g10b10, fetch_scanline_x2r10g10b10_float,
+      fetch_pixel_generic_lossy_32, fetch_pixel_x2r10g10b10, fetch_pixel_x2r10g10b10_float,
+      NULL, store_scanline_x2r10g10b10, store_scanline_x2r10g10b10_float },
     
     { PIXMAN_a2b10g10r10,
-      NULL, fetch_scanline_a2b10g10r10,
-      fetch_pixel_generic_lossy_32, fetch_pixel_a2b10g10r10,
-      NULL, store_scanline_a2b10g10r10 },
+      NULL, fetch_scanline_a2b10g10r10, fetch_scanline_a2b10g10r10_float,
+      fetch_pixel_generic_lossy_32, fetch_pixel_a2b10g10r10, fetch_pixel_a2b10g10r10_float,
+      NULL, store_scanline_a2b10g10r10, store_scanline_a2b10g10r10_float },
     
     { PIXMAN_x2b10g10r10,
-      NULL, fetch_scanline_x2b10g10r10,
-      fetch_pixel_generic_lossy_32, fetch_pixel_x2b10g10r10,
-      NULL, store_scanline_x2b10g10r10 },
+      NULL, fetch_scanline_x2b10g10r10, fetch_scanline_x2b10g10r10_float,
+      fetch_pixel_generic_lossy_32, fetch_pixel_x2b10g10r10, fetch_pixel_x2b10g10r10_float,
+      NULL, store_scanline_x2b10g10r10, store_scanline_x2b10g10r10_float },
     
 /* YUV formats */
     { PIXMAN_yuy2,
-      fetch_scanline_yuy2, fetch_scanline_generic_64,
-      fetch_pixel_yuy2, fetch_pixel_generic_64,
-      NULL, NULL },
+      fetch_scanline_yuy2, fetch_scanline_generic_64, fetch_scanline_generic_float,
+      fetch_pixel_yuy2, fetch_pixel_generic_64, fetch_pixel_generic_float,
+      NULL, NULL, NULL },
     
     { PIXMAN_yv12,
-      fetch_scanline_yv12, fetch_scanline_generic_64,
-      fetch_pixel_yv12, fetch_pixel_generic_64,
+      fetch_scanline_yv12, fetch_scanline_generic_64, fetch_scanline_generic_float,
+      fetch_pixel_yv12, fetch_pixel_generic_64, fetch_pixel_generic_float,
       NULL, NULL },
     
     { PIXMAN_null },
@@ -1313,10 +1857,13 @@ setup_accessors (bits_image_t *image)
 	{
 	    image->fetch_scanline_32 = info->fetch_scanline_32;
 	    image->fetch_scanline_64 = info->fetch_scanline_64;
+	    image->fetch_scanline_float = info->fetch_scanline_float;
 	    image->fetch_pixel_32 = info->fetch_pixel_32;
 	    image->fetch_pixel_64 = info->fetch_pixel_64;
+	    image->fetch_pixel_float = info->fetch_pixel_float;
 	    image->store_scanline_32 = info->store_scanline_32;
 	    image->store_scanline_64 = info->store_scanline_64;
+	    image->store_scanline_float = info->store_scanline_float;
 	    
 	    return;
 	}
diff --git a/pixman/pixman-bits-image.c b/pixman/pixman-bits-image.c
index c69e151..07353dc 100644
--- a/pixman/pixman-bits-image.c
+++ b/pixman/pixman-bits-image.c
@@ -36,6 +36,20 @@
 #include "pixman-combine32.h"
 #include "pixman-inlines.h"
 
+static uint32_t *
+_pixman_image_get_scanline_generic_float (pixman_iter_t * iter,
+					  const uint32_t *mask)
+{
+    pixman_iter_get_scanline_t fetch_32 = iter->data;
+    uint32_t *buffer = iter->buffer;
+
+    fetch_32 (iter, NULL);
+
+    pixman_expand_to_float ((argb_t *)buffer, buffer, PIXMAN_a8r8g8b8, iter->width);
+
+    return iter->buffer;
+}
+
 /*
  * By default, just evaluate the image at 32bpp and expand.  Individual image
  * types can plug in a better scanline getter if they want to. For example
@@ -1129,6 +1143,7 @@ typedef struct
     uint32_t			flags;
     pixman_iter_get_scanline_t	get_scanline_32;
     pixman_iter_get_scanline_t	get_scanline_64;
+    pixman_iter_get_scanline_t  get_scanline_float;
 } fetcher_info_t;
 
 static const fetcher_info_t fetcher_info[] =
@@ -1140,7 +1155,8 @@ static const fetcher_info_t fetcher_info[] =
        FAST_PATH_NO_PAD_REPEAT			|
        FAST_PATH_NO_REFLECT_REPEAT),
       bits_image_fetch_untransformed_32,
-      bits_image_fetch_untransformed_64
+      bits_image_fetch_untransformed_64,
+      _pixman_image_get_scanline_generic_float
     },
 
 #define FAST_BILINEAR_FLAGS						\
@@ -1156,13 +1172,15 @@ static const fetcher_info_t fetcher_info[] =
     { PIXMAN_a8r8g8b8,
       FAST_BILINEAR_FLAGS,
       bits_image_fetch_bilinear_no_repeat_8888,
-      _pixman_image_get_scanline_generic_64
+      _pixman_image_get_scanline_generic_64,
+      _pixman_image_get_scanline_generic_float
     },
 
     { PIXMAN_x8r8g8b8,
       FAST_BILINEAR_FLAGS,
       bits_image_fetch_bilinear_no_repeat_8888,
-      _pixman_image_get_scanline_generic_64
+      _pixman_image_get_scanline_generic_64,
+      _pixman_image_get_scanline_generic_float
     },
 
 #define GENERAL_BILINEAR_FLAGS						\
@@ -1183,14 +1201,16 @@ static const fetcher_info_t fetcher_info[] =
     { PIXMAN_ ## format,						\
       GENERAL_BILINEAR_FLAGS | FAST_PATH_ ## repeat ## _REPEAT,		\
       bits_image_fetch_bilinear_affine_ ## name,			\
-      _pixman_image_get_scanline_generic_64				\
+      _pixman_image_get_scanline_generic_64,				\
+      _pixman_image_get_scanline_generic_float				\
     },
 
 #define NEAREST_AFFINE_FAST_PATH(name, format, repeat)			\
     { PIXMAN_ ## format,						\
       GENERAL_NEAREST_FLAGS | FAST_PATH_ ## repeat ## _REPEAT,		\
       bits_image_fetch_nearest_affine_ ## name,			\
-      _pixman_image_get_scanline_generic_64				\
+      _pixman_image_get_scanline_generic_64,				\
+      _pixman_image_get_scanline_generic_float				\
     },
 
 #define AFFINE_FAST_PATHS(name, format, repeat)				\
@@ -1218,11 +1238,17 @@ static const fetcher_info_t fetcher_info[] =
     { PIXMAN_any,
       (FAST_PATH_NO_ALPHA_MAP | FAST_PATH_HAS_TRANSFORM | FAST_PATH_AFFINE_TRANSFORM),
       bits_image_fetch_affine_no_alpha,
-      _pixman_image_get_scanline_generic_64
+      _pixman_image_get_scanline_generic_64,
+      _pixman_image_get_scanline_generic_float
     },
 
     /* General */
-    { PIXMAN_any, 0, bits_image_fetch_general, _pixman_image_get_scanline_generic_64 },
+    { PIXMAN_any,
+      0,
+      bits_image_fetch_general,
+      _pixman_image_get_scanline_generic_64,
+      _pixman_image_get_scanline_generic_float
+    },
 
     { PIXMAN_null },
 };
diff --git a/pixman/pixman-private.h b/pixman/pixman-private.h
index 379943e..6a460e7 100644
--- a/pixman/pixman-private.h
+++ b/pixman/pixman-private.h
@@ -70,6 +70,10 @@ typedef uint64_t (*fetch_pixel_64_t) (bits_image_t *image,
 				      int           x,
 				      int           y);
 
+typedef argb_t (*fetch_pixel_float_t) (bits_image_t *image,
+				       int           x,
+				       int           y);
+
 typedef void (*store_scanline_t) (bits_image_t *  image,
 				  int             x,
 				  int             y,
@@ -187,6 +191,10 @@ struct bits_image
     fetch_pixel_64_t	       fetch_pixel_64;
     store_scanline_t           store_scanline_64;
 
+    fetch_scanline_t	       fetch_scanline_float;
+    fetch_pixel_float_t	       fetch_pixel_float;
+    store_scanline_t           store_scanline_float;
+
     /* Used for indirect access to the bits */
     pixman_read_memory_func_t  read_func;
     pixman_write_memory_func_t write_func;