147 lines
2.7 KiB
C
147 lines
2.7 KiB
C
/*
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* io_ss.c
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*
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* Implements the Source/Sink interface.
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*
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* As will all I/O modules, most functions are for local use only (called
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* via function pointers in the I/O context).
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*
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* The Source/Sink model is the primary 'user' interface for alternate data
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* sources; the IOCtx interface is intended (at least in version 1.5) to be
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* used internally until it settles down a bit.
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*
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* This module just layers the Source/Sink interface on top of the IOCtx; no
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* support is provided for tell/seek, so GD2 writing is not possible, and
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* retrieving parts of GD2 files is also not possible.
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*
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* A new SS context does not need to be created with both a Source and a Sink.
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*
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* Written/Modified 1999, Philip Warner.
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*
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*/
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#ifdef HAVE_CONFIG_H
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# include "config.h"
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#endif
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#include <math.h>
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#include <string.h>
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#include <stdlib.h>
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#include "gd.h"
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#include "gdhelpers.h"
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/* this is used for creating images in main memory */
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typedef struct ssIOCtx {
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gdIOCtx ctx;
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gdSourcePtr src;
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gdSinkPtr snk;
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}
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ssIOCtx;
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typedef struct ssIOCtx *ssIOCtxPtr;
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static int sourceGetbuf(gdIOCtx *, void *, int);
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static int sourceGetchar(gdIOCtx *ctx);
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static int sinkPutbuf(gdIOCtx *ctx, const void *buf, int size);
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static void sinkPutchar(gdIOCtx *ctx, int a);
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static void gdFreeSsCtx(gdIOCtx *ctx);
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/*
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Function: gdNewSSCtx
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Return data as a dynamic pointer.
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*/
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BGD_DECLARE(gdIOCtx *) gdNewSSCtx(gdSourcePtr src, gdSinkPtr snk)
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{
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ssIOCtxPtr ctx;
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ctx = (ssIOCtxPtr)gdMalloc(sizeof (ssIOCtx));
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if (ctx == NULL) {
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return NULL;
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}
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ctx->src = src;
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ctx->snk = snk;
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ctx->ctx.getC = sourceGetchar;
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ctx->ctx.getBuf = sourceGetbuf;
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ctx->ctx.putC = sinkPutchar;
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ctx->ctx.putBuf = sinkPutbuf;
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ctx->ctx.tell = NULL;
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ctx->ctx.seek = NULL;
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ctx->ctx.gd_free = gdFreeSsCtx;
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return (gdIOCtx *)ctx;
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}
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static void gdFreeSsCtx(gdIOCtx *ctx)
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{
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gdFree(ctx);
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}
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static int sourceGetbuf(gdIOCtx *ctx, void *buf, int size)
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{
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ssIOCtx *lctx;
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int res;
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lctx = (ssIOCtx *)ctx;
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res = ((lctx->src->source)(lctx->src->context, buf, size));
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/*
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* Translate the return values from the Source object:
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* 0 is EOF, -1 is error
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*/
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if (res == 0) {
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return 0;
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} else if (res < 0) {
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return 0;
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} else {
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return res;
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}
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}
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static int sourceGetchar(gdIOCtx *ctx)
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{
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int res;
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unsigned char buf;
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res = sourceGetbuf(ctx, &buf, 1);
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if (res == 1) {
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return buf;
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} else {
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return EOF;
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}
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}
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static int sinkPutbuf(gdIOCtx *ctx, const void *buf, int size)
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{
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ssIOCtxPtr lctx;
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int res;
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lctx = (ssIOCtx *)ctx;
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res = (lctx->snk->sink)(lctx->snk->context, buf, size);
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if (res <= 0) {
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return 0;
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} else {
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return res;
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}
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}
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static void sinkPutchar(gdIOCtx *ctx, int a)
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{
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unsigned char b;
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b = a;
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sinkPutbuf(ctx, &b, 1);
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}
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