UVLC decoding tables used to partially decode u values from UVLC
codewords. More...

Functions
static bool	grk::t1::ojph::local::uvlc_init_tables ()
	Initializes uvlc_tbl0 and uvlc_tbl1 tables.

Variables
ui16	grk::t1::ojph::local::uvlc_tbl0 [256+64] = { 0 }
	uvlc_tbl0 contains decoding information for initial row of quads
ui16	grk::t1::ojph::local::uvlc_tbl1 [256] = { 0 }
	uvlc_tbl1 contains decoding information for non-initial row of quads
ui8	grk::t1::ojph::local::uvlc_bias [256+64] = { 0 }
	uvlc_bias contains decoding info. for initial row of quads
static bool	grk::t1::ojph::local::uvlc_tables_initialized = uvlc_init_tables()
	Initializes UVLC tables uvlc_tbl0 and uvlc_tbl1.

Detailed Description

UVLC decoding tables used to partially decode u values from UVLC
codewords.

The table index is 8 (or 9) bits and composed of two parts:
The 6 LSBs carries the head of the VLC to be decoded. Up to 6 bits to be used; these are uvlc prefix code for quad 0 and 1
The 2 (or 3) MSBs contain u_off of quad 0 + 2 * o_off quad 1

4 * mel event for initial row of quads when needed

Each entry contains, starting from the LSB
- total total prefix length for quads 0 and 1 (3 bits)
- total total suffix length for quads 0 and 1 (4 bits)
- suffix length for quad 0 (3 bits)
- prefix for quad 0 (3 bits)
- prefix for quad 1 (3 bits)
  
  Another table is uvlc_bias, which is needed to correctly decode the extension u_ext for initial row of quads. Under certain condition, we deduct 1 or 2 from u_q0 and u_q1 before encoding them; so for us to know that decoding u_ext is needed, we recreate the u_q0 and u_q1 that we actually encoded.
  For simplicity, we use the same index as before
- u_q0 bias is 2 bits
- u_q1 bias is 2 bits

Function Documentation

◆ uvlc_init_tables()

bool grk::t1::ojph::local::uvlc_init_tables ( )

static

Initializes uvlc_tbl0 and uvlc_tbl1 tables.

References uvlc_bias, uvlc_tbl0, and uvlc_tbl1.

Referenced by initialize_block_encoder_tables().

Variable Documentation

◆ uvlc_bias

ui8 grk::t1::ojph::local::uvlc_bias = { 0 }

uvlc_bias contains decoding info. for initial row of quads

Referenced by ojph_decode_codeblock64(), and uvlc_init_tables().

◆ uvlc_tables_initialized

bool grk::t1::ojph::local::uvlc_tables_initialized = uvlc_init_tables()

static

Initializes UVLC tables uvlc_tbl0 and uvlc_tbl1.

◆ uvlc_tbl0

ui16 grk::t1::ojph::local::uvlc_tbl0 = { 0 }

uvlc_tbl0 contains decoding information for initial row of quads

Referenced by ojph_decode_codeblock32(), ojph_decode_codeblock64(), ojph_decode_codeblock_wasm(), and uvlc_init_tables().

◆ uvlc_tbl1

ui16 grk::t1::ojph::local::uvlc_tbl1 = { 0 }

uvlc_tbl1 contains decoding information for non-initial row of quads