harvey/sys/src/cmd/gs/src/szlibd.c

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*/

/*$Id: szlibd.c,v 1.3 2000/11/01 22:36:13 lpd Exp $ */
/* zlib decoding (decompression) filter stream */
#include "std.h"
#include "gsmemory.h"
#include "gsmalloc.h"		/* for gs_memory_default */
#include "strimpl.h"
#include "szlibxx.h"

/* Initialize the filter. */
private int
s_zlibD_init(stream_state * st)
{
    stream_zlib_state *const ss = (stream_zlib_state *)st;
    int code = s_zlib_alloc_dynamic_state(ss);

    if (code < 0)
	return ERRC;	/****** WRONG ******/
    if (inflateInit2(&ss->dynamic->zstate,
		     (ss->no_wrapper ? -ss->windowBits : ss->windowBits))
	!= Z_OK
	) {
	s_zlib_free_dynamic_state(ss);
	return ERRC;	/****** WRONG ******/
    }
    st->min_left=1;
    return 0;
}

/* Reinitialize the filter. */
private int
s_zlibD_reset(stream_state * st)
{
    stream_zlib_state *const ss = (stream_zlib_state *)st;

    if (inflateReset(&ss->dynamic->zstate) != Z_OK)
	return ERRC;	/****** WRONG ******/
    return 0;
}

/* Process a buffer */
private int
s_zlibD_process(stream_state * st, stream_cursor_read * pr,
		stream_cursor_write * pw, bool ignore_last)
{
    stream_zlib_state *const ss = (stream_zlib_state *)st;
    z_stream *zs = &ss->dynamic->zstate;
    const byte *p = pr->ptr;
    int status;

    /* Detect no input or full output so that we don't get */
    /* a Z_BUF_ERROR return. */
    if (pw->ptr == pw->limit)
	return 1;
    if (pr->ptr == pr->limit)
	return 0;
    zs->next_in = (Bytef *)p + 1;
    zs->avail_in = pr->limit - p;
    zs->next_out = pw->ptr + 1;
    zs->avail_out = pw->limit - pw->ptr;
    status = inflate(zs, Z_PARTIAL_FLUSH);
    pr->ptr = zs->next_in - 1;
    pw->ptr = zs->next_out - 1;
    switch (status) {
	case Z_OK:
	    return (pw->ptr == pw->limit ? 1 : pr->ptr > p ? 0 : 1);
	case Z_STREAM_END:
	    return EOFC;
	default:
	    return ERRC;
    }
}

/* Release the stream */
private void
s_zlibD_release(stream_state * st)
{
    stream_zlib_state *const ss = (stream_zlib_state *)st;

    inflateEnd(&ss->dynamic->zstate);
    s_zlib_free_dynamic_state(ss);
}

/* Stream template */
const stream_template s_zlibD_template = {
    &st_zlib_state, s_zlibD_init, s_zlibD_process, 1, 1, s_zlibD_release,
    s_zlib_set_defaults, s_zlibD_reset
};