[FFmpeg-devel] [PATCH 02/15] libavutil: Implementation of AAC_fixed_decoder (LC-module) [2/5]
Michael Niedermayer
michaelni at gmx.at
Sat Nov 8 15:02:32 CET 2014
On Fri, Nov 07, 2014 at 04:08:06PM +0100, Nedeljko Babic wrote:
> From: Djordje Pesut <djordje.pesut at imgtec.com>
>
> Make changes in softfloat.
>
> Functions for sqrt and sincos are added.
>
> Div function is improved.
>
> Some changes are made in order for code in softfloat to be usable in fixed aac
> decoder code.
> For example order of fields in structure SoftFloat is changed.
> This doesn't create any impact on current ffmpeg code since softfloat is
> currently not in use and this way we don't need to make much changes in
> implementation of aac fixed point decoder that uses this code.
>
> Signed-off-by: Nedeljko Babic <nedeljko.babic at imgtec.com>
> ---
> libavutil/softfloat.h | 167 ++++++++++++++++++++----
> libavutil/softfloat_tables.h | 294 +++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 439 insertions(+), 22 deletions(-)
> create mode 100644 libavutil/softfloat_tables.h
>
> diff --git a/libavutil/softfloat.h b/libavutil/softfloat.h
> index 8647e6a..df91a8b 100644
> --- a/libavutil/softfloat.h
> +++ b/libavutil/softfloat.h
> @@ -23,18 +23,26 @@
>
> #include <stdint.h>
> #include "common.h"
> -
> #include "avassert.h"
> +#include "softfloat_tables.h"
>
> #define MIN_EXP -126
> #define MAX_EXP 126
> #define ONE_BITS 29
>
> typedef struct SoftFloat{
> - int32_t exp;
> int32_t mant;
> + int32_t exp;
> }SoftFloat;
>
> +static const SoftFloat FLOAT_0 = { 0, 0};
> +static const SoftFloat FLOAT_05 = { 536870912, 0};
> +static const SoftFloat FLOAT_1 = { 536870912, 1};
> +static const SoftFloat FLOAT_EPSILON = { 703687442, -16};
> +static const SoftFloat FLOAT_1584893192 = { 850883053, 1};
> +static const SoftFloat FLOAT_100000 = { 819200000, 17};
> +static const SoftFloat FLOAT_0999999 = {1073740750, 0};
the mantises should be in some form of base 2 or base 16 in the
source as this should be more readable
> +
> static av_const SoftFloat av_normalize_sf(SoftFloat a){
> if(a.mant){
> #if 1
> @@ -66,11 +74,12 @@ static inline av_const SoftFloat av_normalize1_sf(SoftFloat a){
> av_assert2(a.mant < 0x40000000 && a.mant > -0x40000000);
> return a;
> #elif 1
> - int t= a.mant + 0x40000000 < 0;
> - return (SoftFloat){a.exp+t, a.mant>>t};
> + int t= a.mant + 0x40000000;
> + t = t < 0;
> + return (SoftFloat){ a.mant>>t, a.exp+t};
> #else
> int t= (a.mant + 0x40000000U)>>31;
> - return (SoftFloat){a.exp+t, a.mant>>t};
> + return (SoftFloat){a.mant>>t, a.exp+t};
fliping the order of the argumets, as its cosmetic should be in a
seperate patch from all functional changes
this keeps the changes easier to read now for review as well as in
the future
[...]
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
When you are offended at any man's fault, turn to yourself and study your
own failings. Then you will forget your anger. -- Epictetus
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