X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=input.h;h=34765c25b113b35efff8c77ccf4d3f3e09ae30f0;hb=71b4fae2b31acf415c3b07a019ae252f4d128952;hp=28c5f0b8530e820101063cef9c0ab83ea6aa0748;hpb=6d281fa9f39dd23ee8ee432cd35927b085303aa1;p=fjl diff --git a/input.h b/input.h index 28c5f0b..34765c2 100644 --- a/input.h +++ b/input.h @@ -21,11 +21,13 @@ static const unsigned bitreservoir_size = 8 * sizeof(bitreservoir_t); static const unsigned bitreservoir_fill_size = 8 * sizeof(bitreservoir_fill_t); static const unsigned bytereservoir_size = 4096; -// A function to read bytes from some input source. +// A function to read bytes from some input source. The bytes should be +// already unstuffed (and thus without markers). // A return value of -1 indicates error, a return value of 0 indicates EOF. typedef ssize_t (input_func_t)(void*, uint8_t*, size_t); -struct data_source { +// A data source for efficient reading of bit-level data. +struct bit_source { // Short-term bit reservoir; holds up to 64 bits. When it's empty, // it needs to get refilled from the medium-term bit reservoir. bitreservoir_t bits; @@ -41,17 +43,17 @@ struct data_source { input_func_t* input_func; void* userdata; }; - -void init_data_source(struct data_source* source, input_func_t* input_func, void* userdata); + +void init_bit_source(struct bit_source* source, input_func_t* input_func, void* userdata); // Internal function. Do not use. -void possibly_refill_slow_path(struct data_source* source, unsigned num_bits); +void possibly_refill_slow_path(struct bit_source* source, unsigned num_bits); // Make sure there's at least NUM_BITS available in the short-term bit reservoir. // You usually want to call this before read_bits(). The reason it's separate // is that if you want two reads and you know the size of both, it's faster to // refill A+B, read A, read B than refill A, read A, refill B, read B. -static inline void possibly_refill(struct data_source* source, unsigned num_bits) +static inline void possibly_refill(struct bit_source* source, unsigned num_bits) { assert(num_bits <= bitreservoir_fill_size + 1); @@ -76,7 +78,7 @@ static inline void possibly_refill(struct data_source* source, unsigned num_bits possibly_refill_slow_path(source, num_bits); } -static inline unsigned read_bits(struct data_source* source, unsigned num_bits) +static inline unsigned read_bits(struct bit_source* source, unsigned num_bits) { assert(source->bits_available >= num_bits); unsigned ret = (source->bits >> (bitreservoir_size - num_bits));