delta_encoder.c File Reference

Delta filter encoder. More...

#include "delta_encoder.h"
#include "delta_private.h"

Go to the source code of this file.

Functions
static void	copy_and_encode (lzma_delta_coder *coder, const uint8_t *restrict in, uint8_t *restrict out, size_t size)
static void	encode_in_place (lzma_delta_coder *coder, uint8_t *buffer, size_t size)
static lzma_ret	delta_encode (void *coder_ptr, const lzma_allocator *allocator, const uint8_t *restrict in, size_t *restrict in_pos, size_t in_size, uint8_t *restrict out, size_t *restrict out_pos, size_t out_size, lzma_action action)
static lzma_ret	delta_encoder_update (void *coder_ptr, const lzma_allocator *allocator, const lzma_filter *filters_null lzma_attribute((__unused__)), const lzma_filter *reversed_filters)
lzma_ret	lzma_delta_encoder_init (lzma_next_coder *next, const lzma_allocator *allocator, const lzma_filter_info *filters)
lzma_ret	lzma_delta_props_encode (const void *options, uint8_t *out)

Detailed Description

Delta filter encoder.

Definition in file delta_encoder.c.

Function Documentation

copy_and_encode()

static void copy_and_encode ( lzma_delta_coder *  coder, const uint8_t *restrict  in, uint8_t *restrict  out, size_t  size  )

static

Copies and encodes the data at the same time. This is used when Delta is the first filter in the chain (and thus the last filter in the encoder's filter stack).

Definition at line 21 of file delta_encoder.c.

{
    const size_t distance = coder->distance;
 
    for (size_t i = 0; i < size; ++i) {
        const uint8_t tmp = coder->history[
                (distance + coder->pos) & 0xFF];
        coder->history[coder->pos-- & 0xFF] = in[i];
        out[i] = in[i] - tmp;
    }
}

References lzma_delta_coder::distance, lzma_delta_coder::history, i, in, out, lzma_delta_coder::pos, and autogen_x86imm::tmp.

Referenced by delta_encode().

delta_encode()

static lzma_ret delta_encode ( void *  coder_ptr, const lzma_allocator *  allocator, const uint8_t *restrict  in, size_t *restrict  in_pos, size_t  in_size, uint8_t *restrict  out, size_t *restrict  out_pos, size_t  out_size, lzma_action  action  )

static

Definition at line 52 of file delta_encoder.c.

{
    lzma_delta_coder *coder = coder_ptr;
 
    lzma_ret ret;
 
    if (coder->next.code == NULL) {
        const size_t in_avail = in_size - *in_pos;
        const size_t out_avail = out_size - *out_pos;
        const size_t size = my_min(in_avail, out_avail);
 
        copy_and_encode(coder, in + *in_pos, out + *out_pos, size);
 
        *in_pos += size;
        *out_pos += size;
 
        ret = action != LZMA_RUN && *in_pos == in_size
                ? LZMA_STREAM_END : LZMA_OK;
 
    } else {
        const size_t out_start = *out_pos;
 
        ret = coder->next.code(coder->next.coder, allocator,
                in, in_pos, in_size, out, out_pos, out_size,
                action);
 
        encode_in_place(coder, out + out_start, *out_pos - out_start);
    }
 
    return ret;
}

References test-lz4-speed::action, allocator, lzma_next_coder_s::code, lzma_next_coder_s::coder, copy_and_encode(), encode_in_place(), in, in_pos, in_size, LZMA_OK, LZMA_RUN, LZMA_STREAM_END, my_min, lzma_delta_coder::next, NULL, out, and out_pos.

Referenced by lzma_delta_encoder_init().

delta_encoder_update()

static lzma_ret delta_encoder_update ( void *  coder_ptr, const lzma_allocator *  allocator, const lzma_filter *filters_null   lzma_attribute(__unused__), const lzma_filter *  reversed_filters  )

static

Definition at line 89 of file delta_encoder.c.

{
    lzma_delta_coder *coder = coder_ptr;
 
    // Delta doesn't and will never support changing the options in
    // the middle of encoding. If the app tries to change them, we
    // simply ignore them.
    return lzma_next_filter_update(
            &coder->next, allocator, reversed_filters + 1);
}

References allocator, lzma_next_filter_update(), and lzma_delta_coder::next.

Referenced by lzma_delta_encoder_init().

encode_in_place()

static void encode_in_place ( lzma_delta_coder *  coder, uint8_t *  buffer, size_t  size  )

static

Encodes the data in place. This is used when we are the last filter in the chain (and thus non-last filter in the encoder's filter stack).

Definition at line 38 of file delta_encoder.c.

{
    const size_t distance = coder->distance;
 
    for (size_t i = 0; i < size; ++i) {
        const uint8_t tmp = coder->history[
                (distance + coder->pos) & 0xFF];
        coder->history[coder->pos-- & 0xFF] = buffer[i];
        buffer[i] -= tmp;
    }
}

References lzma_delta_coder::distance, lzma_delta_coder::history, i, lzma_delta_coder::pos, and autogen_x86imm::tmp.

Referenced by delta_encode().

lzma_delta_encoder_init()

lzma_ret lzma_delta_encoder_init	(	lzma_next_coder *	next,
		const lzma_allocator *	allocator,
		const lzma_filter_info *	filters
	)

Definition at line 104 of file delta_encoder.c.

{
    next->code = &delta_encode;
    next->update = &delta_encoder_update;
    return lzma_delta_coder_init(next, allocator, filters);
}

References allocator, lzma_next_coder_s::code, delta_encode(), delta_encoder_update(), filters, lzma_delta_coder_init(), and lzma_next_coder_s::update.

lzma_delta_props_encode()

lzma_ret lzma_delta_props_encode	(	const void *	options,
		uint8_t *	out
	)

Definition at line 114 of file delta_encoder.c.

{
    // The caller must have already validated the options, so it's
    // LZMA_PROG_ERROR if they are invalid.
    if (lzma_delta_coder_memusage(options) == UINT64_MAX)
        return LZMA_PROG_ERROR;
 
    const lzma_options_delta *opt = options;
    out[0] = opt->dist - LZMA_DELTA_DIST_MIN;
 
    return LZMA_OK;
}

References lzma_options_delta::dist, lzma_delta_coder_memusage(), LZMA_DELTA_DIST_MIN, LZMA_OK, LZMA_PROG_ERROR, options, out, and UINT64_MAX.