[Mesa-dev] [PATCH 01/10] i965: Add functions to convert float <-> VF.

[Matt Turner]

On Thu, Oct 23, 2014 at 11:01 PM, Ville Syrjälä <syrjala at sci.fi> wrote:
> On Thu, Oct 23, 2014 at 04:44:03PM -0700, Matt Turner wrote:
>> ---
>>  src/mesa/drivers/dri/i965/Makefile.sources   |  1 +
>>  src/mesa/drivers/dri/i965/brw_packed_float.c | 74 ++++++++++++++++++++++++++++
>>  src/mesa/drivers/dri/i965/brw_packed_float.h | 25 ++++++++++
>>  3 files changed, 100 insertions(+)
>>  create mode 100644 src/mesa/drivers/dri/i965/brw_packed_float.c
>>  create mode 100644 src/mesa/drivers/dri/i965/brw_packed_float.h
>>
>> diff --git a/src/mesa/drivers/dri/i965/Makefile.sources b/src/mesa/drivers/dri/i965/Makefile.sources
>> index 9c006da..6b0f601 100644
>> --- a/src/mesa/drivers/dri/i965/Makefile.sources
>> +++ b/src/mesa/drivers/dri/i965/Makefile.sources
>> @@ -78,6 +78,7 @@ i965_FILES = \
>>       brw_meta_fast_clear.c \
>>       brw_misc_state.c \
>>       brw_object_purgeable.c \
>> +     brw_packed_float.c \
>>       brw_performance_monitor.c \
>>       brw_program.c \
>>       brw_primitive_restart.c \
>> diff --git a/src/mesa/drivers/dri/i965/brw_packed_float.c b/src/mesa/drivers/dri/i965/brw_packed_float.c
>> new file mode 100644
>> index 0000000..d25e7dd
>> --- /dev/null
>> +++ b/src/mesa/drivers/dri/i965/brw_packed_float.c
>> @@ -0,0 +1,74 @@
>> +/*
>> + * Copyright © 2014 Intel Corporation
>> + *
>> + * Permission is hereby granted, free of charge, to any person obtaining a
>> + * copy of this software and associated documentation files (the "Software"),
>> + * to deal in the Software without restriction, including without limitation
>> + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
>> + * and/or sell copies of the Software, and to permit persons to whom the
>> + * Software is furnished to do so, subject to the following conditions:
>> + *
>> + * The above copyright notice and this permission notice (including the next
>> + * paragraph) shall be included in all copies or substantial portions of the
>> + * Software.
>> + *
>> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
>> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
>> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
>> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
>> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
>> + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
>> + * IN THE SOFTWARE.
>> + */
>> +#include "brw_packed_float.h"
>> +
>> +union fu {
>> +   float f;
>> +   unsigned u;
>> +   struct {
>> +      unsigned mantissa:23;
>> +      unsigned exponent:8;
>> +      unsigned sign:1;
>> +   };
>> +};
>> +
>> +int
>> +brw_float_to_vf(float f)
>> +{
>> +   union fu fu = { .f = f };
>> +
>> +   /* ±0.0f is special cased. */
>> +   if (f == 0.0f)
>> +      return fu.sign << 7;
>> +
>> +   unsigned mantissa = fu.mantissa >> (23 - 4);
>> +   unsigned exponent = fu.exponent - (127 - 3);
>
> & 0x7

No, the exponent >= 8 below handles that.