SFDC Text Compression Algorithm

The SFDC algorithm is designed for efficient text compression, particularly optimized for files with 4-byte values. The algorithm maintains all pending bits on the dynamic layer, ensuring effective compression and decompression of text data.

Features

• Dynamic Layer Management: All pending bits are maintained on the dynamic layer for optimized performance.
• 4-Byte Value Optimization: Specifically tuned for files containing 4-byte values.
• Efficient Encoding and Decoding: Utilizes a stack-based approach to manage encoding and decoding processes.

Functions

uint32_t **delta_encode(int *y, int n, uint64_t *map, int *codelen, int nlayers, double *avgdelay, double *avgbits, int *max_char, int idx)

Encodes the input text using the SFDC delta variant algorithm.

Parameters

• int *y: Input array of integers representing the text to be encoded.
• int n: Length of the input text.
• uint64_t *map: Mapping of characters to their corresponding codes.
• int *codelen: Array containing the length of each code.
• int nlayers: Number of fixed layers in the compression scheme.
• double *avgdelay: Output parameter for the average delay in encoding.
• double *avgbits: Output parameter for the average bits per character.
• int *max_char: Output parameter for the character with the maximum delay.
• int idx: Index parameter for encoding context.

Returns

• uint32_t **: A pointer to the encoded representation of the text.

int delta_decode(uint32_t **blce, int i, int j, int nlayers, HNODE *root, int n, int *dt, STACKNODE *stack)

Decodes the encoded text using the SFDC delta variant algorithm.

Parameters

• uint32_t **blce: The encoded representation of the text.
• int i: Starting position of the window to decode.
• int j: Ending position of the window to decode (for a single character, i=j).
• int nlayers: Number of fixed layers in the encoded text.
• HNODE *root: Root of the Huffman tree used for decoding.
• int n: Length of the text.
• int *dt: Array to store the decoded text.
• STACKNODE *stack: Stack used for managing the decoding process.

Returns

• int: The position of the last decoded character.