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fourcc: use binary rather than linear search
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Rémi Denis-Courmont committed Jun 11, 2015
1 parent 9e6b1f9 commit 165861e
Showing 1 changed file with 66 additions and 93 deletions.
159 changes: 66 additions & 93 deletions src/misc/fourcc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -33,115 +33,89 @@
#include <vlc_es.h>
#include <assert.h>

#include "fourcc_tables.h"

typedef struct
static int fourcc_cmp(const void *key, const void *ent)
{
char p_class[4];
char p_fourcc[4];
char psz_description[56];
} staticentry_t;

typedef struct
{
char p_class[4];
char p_fourcc[4];
const char *psz_description;
} entry_t;

#define NULL4 "\x00\x00\x00\x00"

/* XXX You don't want to see the preprocessor generated code ;) */
#ifdef WORDS_BIGENDIAN
# define FCC2STR(f) { ((f)>>24)&0xff, ((f)>>16)&0xff, ((f)>>8)&0xff, ((f)>>0)&0xff }
#else
# define FCC2STR(f) { ((f)>>0)&0xff, ((f)>>8)&0xff, ((f)>>16)&0xff, ((f)>>24)&0xff }
#endif
/* Begin a new class */
#define B(a, c) { .p_class = FCC2STR(a), .p_fourcc = FCC2STR(a), .psz_description = c }
/* Create a sub-class entry with description */
#define E(b, c) { .p_class = NULL4, .p_fourcc = b, .psz_description = c }
/* Create a sub-class entry without description (alias) */
#define A(b) E(b, NULL4)

#include "misc/fourcc_list.h"

/* Create a fourcc from a string.
* XXX it assumes that the string is at least four bytes */
static inline vlc_fourcc_t CreateFourcc( const char *psz_fourcc )
{
return VLC_FOURCC( psz_fourcc[0], psz_fourcc[1],
psz_fourcc[2], psz_fourcc[3] );
return memcmp(key, ent, 4);
}

/* */
static entry_t Lookup( const staticentry_t p_list[], vlc_fourcc_t i_fourcc )
static vlc_fourcc_t Lookup(vlc_fourcc_t fourcc, const char **restrict dsc,
const struct fourcc_mapping *mapv, size_t mapc,
const struct fourcc_desc *dscv, size_t dscc)
{
const char *p_class = NULL;
const char *psz_description = NULL;

entry_t e = B(0, "");
const struct fourcc_mapping *mapping;
const struct fourcc_desc *desc;

for( int i = 0; ; i++ )
mapping = bsearch(&fourcc, mapv, mapc, sizeof (*mapv), fourcc_cmp);
if (mapping != NULL)
{
const staticentry_t *p = &p_list[i];
const vlc_fourcc_t i_entry_fourcc = CreateFourcc( p->p_fourcc );
const vlc_fourcc_t i_entry_class = CreateFourcc( p->p_class );

if( i_entry_fourcc == 0 )
break;

if( i_entry_class != 0 )
if (dsc != NULL)
{
p_class = p->p_class;
psz_description = p->psz_description;
desc = bsearch(&fourcc, dscv, dscc, sizeof (*dscv), fourcc_cmp);
if (desc != NULL)
{
*dsc = desc->desc;
return mapping->fourcc;
}
}
fourcc = mapping->fourcc;
}

if( i_entry_fourcc == i_fourcc )
{
assert( p_class != NULL );
desc = bsearch(&fourcc, dscv, dscc, sizeof (*dscv), fourcc_cmp);
if (desc == NULL)
return 0; /* Unknown FourCC */
if (dsc != NULL)
*dsc = desc->desc;
return fourcc; /* Known FourCC (has a description) */
}

memcpy( e.p_class, p_class, 4 );
memcpy( e.p_fourcc, p->p_fourcc, 4 );
e.psz_description = p->psz_description[0] != '\0' ?
p->psz_description : psz_description;
break;
}
}
return e;
static vlc_fourcc_t LookupVideo(vlc_fourcc_t fourcc, const char **restrict dsc)
{
return Lookup(fourcc, dsc, mapping_video,
sizeof (mapping_video) / sizeof (mapping_video[0]),
desc_video, sizeof (desc_video) / sizeof (desc_video[0]));
}

/* */
static entry_t Find( int i_cat, vlc_fourcc_t i_fourcc )
static vlc_fourcc_t LookupAudio(vlc_fourcc_t fourcc, const char **restrict dsc)
{
entry_t e;
return Lookup(fourcc, dsc, mapping_audio,
sizeof (mapping_audio) / sizeof (mapping_audio[0]),
desc_audio, sizeof (desc_audio) / sizeof (desc_audio[0]));
}

switch( i_cat )
static vlc_fourcc_t LookupSpu(vlc_fourcc_t fourcc, const char **restrict dsc)
{
return Lookup(fourcc, dsc, mapping_spu,
sizeof (mapping_spu) / sizeof (mapping_spu[0]),
desc_spu, sizeof (desc_spu) / sizeof (desc_spu[0]));
}

static vlc_fourcc_t LookupCat(vlc_fourcc_t fourcc, const char **restrict dsc,
int cat)
{
switch (cat)
{
case VIDEO_ES:
return Lookup( p_list_video, i_fourcc );
case AUDIO_ES:
return Lookup( p_list_audio, i_fourcc );
case SPU_ES:
return Lookup( p_list_spu, i_fourcc );

default:
e = Lookup( p_list_video, i_fourcc );
if( CreateFourcc( e.p_class ) == 0 )
e = Lookup( p_list_audio, i_fourcc );
if( CreateFourcc( e.p_class ) == 0 )
e = Lookup( p_list_spu, i_fourcc );
return e;
case VIDEO_ES:
return LookupVideo(fourcc, dsc);
case AUDIO_ES:
return LookupAudio(fourcc, dsc);
case SPU_ES:
return LookupSpu(fourcc, dsc);
}

vlc_fourcc_t ret = LookupVideo(fourcc, dsc);
if (!ret)
ret = LookupAudio(fourcc, dsc);
if (!ret)
ret = LookupSpu(fourcc, dsc);
return ret;
}

/* */
vlc_fourcc_t vlc_fourcc_GetCodec( int i_cat, vlc_fourcc_t i_fourcc )
vlc_fourcc_t vlc_fourcc_GetCodec(int cat, vlc_fourcc_t fourcc)
{
entry_t e = Find( i_cat, i_fourcc );

if( CreateFourcc( e.p_class ) == 0 )
return i_fourcc;
return CreateFourcc( e.p_class );
vlc_fourcc_t codec = LookupCat(fourcc, NULL, cat);
return codec ? codec : fourcc;
}

vlc_fourcc_t vlc_fourcc_GetCodecFromString( int i_cat, const char *psz_fourcc )
Expand Down Expand Up @@ -224,12 +198,11 @@ vlc_fourcc_t vlc_fourcc_GetCodecAudio( vlc_fourcc_t i_fourcc, int i_bits )
}
}

/* */
const char *vlc_fourcc_GetDescription( int i_cat, vlc_fourcc_t i_fourcc )
const char *vlc_fourcc_GetDescription(int cat, vlc_fourcc_t fourcc)
{
entry_t e = Find( i_cat, i_fourcc );
const char *ret;

return e.psz_description;
return LookupCat(fourcc, &ret, cat) ? ret : "";
}


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