GL_EXT_packed_float, 2.1.B Unsigned 10-Bit Floating-Point Numbers:
0.0, if E == 0 and M == 0,
2^-14 * (M / 32), if E == 0 and M != 0,
2^(E-15) * (1 + M/32), if 0 < E < 31,
INF, if E == 31 and M == 0, or
NaN, if E == 31 and M != 0,
In the second case (E == 0 and M != 0), we were multiplying the mantissa
by 2^-20, when we should have been multiplying by 2^-19 (which is
2^(-14 + -5), or 2^-14 * 2^-5, or 2^-14 / 32).
The previous section defines the formula for 11-bit numbers, which is:
2^-14 * (M / 64), if E == 0 and M != 0,
In other words, we had accidentally copy and pasted the 11-bit code
to the 10-bit case, and neglected to change the exponent.
Fixes dEQP-GLES3.functional.pbo.renderbuffer.r11f_g11f_b10f_triangles
when run with surface dimensions of 1536x1152 or 1920x1080.
References: https://code.google.com/p/chrome-os-partner/issues/detail?id=56244
Signed-off-by: Kenneth Graunke <[email protected]>
Reviewed-by: Stephane Marchesin <[email protected]>
---
src/util/format_r11g11b10f.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/src/util/format_r11g11b10f.h b/src/util/format_r11g11b10f.h
index c9e967c..f6cd4ac 100644
--- a/src/util/format_r11g11b10f.h
+++ b/src/util/format_r11g11b10f.h
@@ -191,7 +191,7 @@ static inline float uf10_to_f32(uint16_t val)
if (exponent == 0) {
if (mantissa != 0) {
- const float scale = 1.0 / (1 << 20);
+ const float scale = 1.0 / (1 << 19);
f32.f = scale * mantissa;
}
} else if (exponent == 31) {
--
2.9.3
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