/*

 * io_ss.c

 *

 * Implements the Source/Sink interface.

 *

 * As will all I/O modules, most functions are for local use only (called

 * via function pointers in the I/O context).

 *

 * The Source/Sink model is the primary 'user' interface for alternate data

 * sources; the IOCtx interface is intended (at least in version 1.5) to be

 * used internally until it settles down a bit.

 *

 * This module just layers the Source/Sink interface on top of the IOCtx; no

 * support is provided for tell/seek, so GD2 writing is not possible, and

 * retrieving parts of GD2 files is also not possible.

 *

 * A new SS context does not need to be created with both a Source and a Sink.

 *

 * Written/Modified 1999, Philip Warner.

 *

 */

#ifdef HAVE_CONFIG_H

#	include "config.h"

#endif

#include <math.h>

#include <string.h>

#include <stdlib.h>

#include "gd.h"

#include "gdhelpers.h"

/* this is used for creating images in main memory */

typedef struct ssIOCtx {

	gdIOCtx ctx;

	gdSourcePtr src;

	gdSinkPtr snk;

}

ssIOCtx;

typedef struct ssIOCtx *ssIOCtxPtr;

static int sourceGetbuf(gdIOCtx *, void *, int);

static int sourceGetchar(gdIOCtx *ctx);

static int sinkPutbuf(gdIOCtx *ctx, const void *buf, int size);

static void sinkPutchar(gdIOCtx *ctx, int a);

static void gdFreeSsCtx(gdIOCtx *ctx);

/*

	Function: gdNewSSCtx

	Return data as a dynamic pointer.

*/

BGD_DECLARE(gdIOCtx *) gdNewSSCtx(gdSourcePtr src, gdSinkPtr snk)

{

	ssIOCtxPtr ctx;

	ctx = (ssIOCtxPtr)gdMalloc(sizeof (ssIOCtx));

	if (ctx == NULL) {

		return NULL;

	}

	ctx->src = src;

	ctx->snk = snk;

	ctx->ctx.getC = sourceGetchar;

	ctx->ctx.getBuf = sourceGetbuf;

	ctx->ctx.putC = sinkPutchar;

	ctx->ctx.putBuf = sinkPutbuf;

	ctx->ctx.tell = NULL;

	ctx->ctx.seek = NULL;

	ctx->ctx.gd_free = gdFreeSsCtx;

	return (gdIOCtx *)ctx;

}

static void gdFreeSsCtx(gdIOCtx *ctx)

{

	gdFree(ctx);

}

static int sourceGetbuf(gdIOCtx *ctx, void *buf, int size)

{

	ssIOCtx *lctx;

	int res;

	lctx = (ssIOCtx *)ctx;

	res = ((lctx->src->source)(lctx->src->context, buf, size));

	/*

	 * Translate the return values from the Source object:

	 * 0 is EOF, -1 is error

	 */

	if (res == 0) {

		return 0;

	} else if (res < 0) {

		return 0;

	} else {

		return res;

	}

}

static int sourceGetchar(gdIOCtx *ctx)

{

	int res;

	unsigned char buf;

	res = sourceGetbuf(ctx, &buf, 1);

	if (res == 1) {

		return buf;

	} else {

		return EOF;

	}

}

static int sinkPutbuf(gdIOCtx *ctx, const void *buf, int size)

{

	ssIOCtxPtr lctx;

	int res;

	lctx = (ssIOCtx *)ctx;

	res = (lctx->snk->sink)(lctx->snk->context, buf, size);

	if (res <= 0) {

		return 0;

	} else {

		return res;

	}

}

static void sinkPutchar(gdIOCtx *ctx, int a)

{

	unsigned char b;

	b = a;

	sinkPutbuf(ctx, &b, 1);

}