bitstreamf.h

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#ifndef BITSTREAMF_H
#define BITSTREAMF_H

#if (defined(__ICCARM__) || defined(__CC_ARM) || (defined(__GNUC__) && (defined(ARM) || defined(__ARM_ARCH_7M__) || defined(__ARM_ARCH_7EM__)))) /* arm */
    #include "ci130x_system.h"
    #include "core_cm4.h"
    #define letoh32(x) (x)
    #define betoh32(x) (uint32_t)__REV(x)
#else

    #define __STATIC_INLINE static inline

    /* Endian conversion routines for standalone compilation */
    #define letoh32(x) (x)
    #define betoh32(x) swap32(x)

    /* Taken from rockbox/firmware/export/system.h */

    __STATIC_INLINE unsigned short swap16(unsigned short value)
    /*
        result[15..8] = value[ 7..0];
        result[ 7..0] = value[15..8];
    */
    {
        return (value >> 8) | (value << 8);
    }

    __STATIC_INLINE unsigned long swap32(unsigned long value)
    /*
        result[31..24] = value[ 7.. 0];
        result[23..16] = value[15.. 8];
        result[15.. 8] = value[23..16];
        result[ 7.. 0] = value[31..24];
    */
    {
        unsigned long hi = swap16(value >> 16);
        unsigned long lo = swap16(value & 0xffff);
        
        return (lo << 16) | hi;
    }
#endif

#define IBSS_ATTR
#define ICONST_ATTR
#define ICODE_ATTR

#ifndef ICODE_ATTR_FLAC
#define ICODE_ATTR_FLAC ICODE_ATTR
#endif

#ifndef IBSS_ATTR_FLAC_DECODED0
#define IBSS_ATTR_FLAC_DECODED0 IBSS_ATTR
#endif




/* FLAC files are big-endian */
#define ALT_BITSTREAM_READER_BE
 
#define NEG_SSR32(a,s) (((int32_t)(a))>>(32-(s)))
#define NEG_USR32(a,s) (((uint32_t)(a))>>(32-(s)))

/* bit input */
/* buffer, buffer_end and size_in_bits must be present and used by every reader */
typedef struct GetBitContext {
    const uint8_t *buffer, *buffer_end;
    int index;
    int size_in_bits;
} GetBitContext;

#define VLC_TYPE int16_t

typedef struct VLC {
    int bits;
    VLC_TYPE (*table)[2]; 
    int table_size, table_allocated;
} VLC;

typedef struct RL_VLC_ELEM {
    int16_t level;
    int8_t len;
    uint8_t run;
} RL_VLC_ELEM;


__STATIC_INLINE uint32_t unaligned32(const void *v) {
    #pragma pack(push)
    #pragma pack(1)
    struct Unaligned {
        uint32_t i;
    };
    #pragma pack(pop)

    return ((struct Unaligned *)v)->i;
}


/* Bitstream reader API docs:
name
    abritary name which is used as prefix for the internal variables

gb
    getbitcontext

OPEN_READER(name, gb)
    loads gb into local variables

CLOSE_READER(name, gb)
    stores local vars in gb

UPDATE_CACHE(name, gb)
    refills the internal cache from the bitstream
    after this call at least MIN_CACHE_BITS will be available,

GET_CACHE(name, gb)
    will output the contents of the internal cache, next bit is MSB of 32 or 64 bit (FIXME 64bit)

SHOW_UBITS(name, gb, num)
    will return the next num bits

SHOW_SBITS(name, gb, num)
    will return the next num bits and do sign extension

SKIP_BITS(name, gb, num)
    will skip over the next num bits
    note, this is equivalent to SKIP_CACHE; SKIP_COUNTER

SKIP_CACHE(name, gb, num)
    will remove the next num bits from the cache (note SKIP_COUNTER MUST be called before UPDATE_CACHE / CLOSE_READER)

SKIP_COUNTER(name, gb, num)
    will increment the internal bit counter (see SKIP_CACHE & SKIP_BITS)

LAST_SKIP_CACHE(name, gb, num)
    will remove the next num bits from the cache if it is needed for UPDATE_CACHE otherwise it will do nothing

LAST_SKIP_BITS(name, gb, num)
    is equivalent to SKIP_LAST_CACHE; SKIP_COUNTER

for examples see get_bits, show_bits, skip_bits, get_vlc
*/

__STATIC_INLINE int unaligned32_be(const void *v){
    return betoh32(unaligned32(v));  // original
}

__STATIC_INLINE int unaligned32_le(const void *v){
    return letoh32(unaligned32(v));  // original
}

#   define MIN_CACHE_BITS 25

#   define OPEN_READER(name, gb)\
        int name##_index= (gb)->index;\
        int name##_cache= 0;\

#   define CLOSE_READER(name, gb)\
        (gb)->index= name##_index;\

#   define UPDATE_CACHE(name, gb)\
        name##_cache= unaligned32_be( ((const uint8_t *)(gb)->buffer)+(name##_index>>3) ) << (name##_index&0x07);\

#   define SKIP_CACHE(name, gb, num)\
        name##_cache <<= (num);


// FIXME name?
#   define SKIP_COUNTER(name, gb, num)\
        name##_index += (num);\

#   define SKIP_BITS(name, gb, num)\
        {\
            SKIP_CACHE(name, gb, num)\
            SKIP_COUNTER(name, gb, num)\
        }\

#   define LAST_SKIP_BITS(name, gb, num) SKIP_COUNTER(name, gb, num)
#   define LAST_SKIP_CACHE(name, gb, num) ;

#   define SHOW_UBITS(name, gb, num)\
        NEG_USR32(name##_cache, num)

#   define SHOW_SBITS(name, gb, num)\
        NEG_SSR32(name##_cache, num)

#   define GET_CACHE(name, gb)\
        ((uint32_t)name##_cache)


__STATIC_INLINE int get_bits_count(GetBitContext *s){
    return s->index;
}

__STATIC_INLINE int get_sbits(GetBitContext *s, int n){
    register int tmp;
    OPEN_READER(re, s)
    UPDATE_CACHE(re, s)
    tmp = SHOW_SBITS(re, s, n);
    LAST_SKIP_BITS(re, s, n)
    CLOSE_READER(re, s)
    return tmp;
}

__STATIC_INLINE unsigned int get_bits(GetBitContext *s, int n){
    register int tmp;
    OPEN_READER(re, s)
    UPDATE_CACHE(re, s)
    tmp = SHOW_UBITS(re, s, n);
    LAST_SKIP_BITS(re, s, n)
    CLOSE_READER(re, s)
    return tmp;
}

__STATIC_INLINE unsigned int show_bits(GetBitContext *s, int n){
    register int tmp;
    OPEN_READER(re, s)
    UPDATE_CACHE(re, s)
    tmp = SHOW_UBITS(re, s, n);
//  CLOSE_READER(re, s)
    return tmp;
}

__STATIC_INLINE void skip_bits(GetBitContext *s, int n){
/*
    OPEN_READER(re, s)
    UPDATE_CACHE(re, s)
    LAST_SKIP_BITS(re, s, n)
    CLOSE_READER(re, s)

    int re_index = s->index;
    unaligned32_be(((const uint8_t *)s->buffer) + (re_index >> 3)) << (re_index & 0x07);
    re_index += n;
    s->index = re_index;
*/
    s->index += n;
}

__STATIC_INLINE unsigned int get_bits1(GetBitContext *s){
    int index = s->index;
    uint8_t result = s->buffer[index >> 3];
    result <<= (index & 0x07);
    result >>= 8 - 1;
    index ++;
    s->index = index;
    return result;
}

__STATIC_INLINE unsigned int show_bits1(GetBitContext *s){
    return show_bits(s, 1);
}

__STATIC_INLINE void skip_bits1(GetBitContext *s){
    skip_bits(s, 1);
}

__STATIC_INLINE void init_get_bits(GetBitContext *s, const uint8_t *buffer, int bit_size){
    int buffer_size= (bit_size+7)>>3;
    if(buffer_size < 0 || bit_size < 0) {
        buffer_size = bit_size = 0;
        buffer = 0;
    }

    s->buffer= buffer;
    s->size_in_bits= bit_size;
    s->buffer_end= buffer + buffer_size;
    s->index=0;
/*
    {
        OPEN_READER(re, s)
        UPDATE_CACHE(re, s)
        UPDATE_CACHE(re, s)
        CLOSE_READER(re, s)
    }
    
    {
        int re_index = s->index;
        unaligned32_be(((const uint8_t *)s->buffer) + (re_index >> 3)) << (re_index & 0x07);
        unaligned32_be(((const uint8_t *)s->buffer) + (re_index >> 3)) << (re_index & 0x07);
        s->index = re_index;
    }
*/
}

void align_get_bits(GetBitContext *s);

#endif /* BITSTREAM_H */