418 lines
9.6 KiB
C
418 lines
9.6 KiB
C
/*-
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* buf.c --
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* Functions for automatically-expanded buffers.
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*
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* Copyright (c) 1987 by the Regents of the University of California
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*
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* Permission to use, copy, modify, and distribute this
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* software and its documentation for any purpose and without
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* fee is hereby granted, provided that the above copyright
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* notice appear in all copies. The University of California
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* makes no representations about the suitability of this
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* software for any purpose. It is provided "as is" without
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* express or implied warranty.
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*
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*
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*/
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#if !defined(lint) && defined(keep_rcsid)
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static char rcsid[] =
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"Header: buf.c,v 1.3 88/09/10 22:36:45 adam Exp $ SPRITE (Berkeley)";
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#endif lint
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#include "sprite.h"
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#include "buf.h"
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typedef struct {
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int size; /* Current size of the buffer */
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Byte *buffer; /* The buffer itself */
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Byte *inPtr; /* Place to write to */
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Byte *outPtr; /* Place to read from */
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} Buf, *BufPtr;
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#ifndef max
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#define max(a,b) ((a) > (b) ? (a) : (b))
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#endif
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/*
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* BufExpand --
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* Expand the given buffer to hold the given number of additional
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* bytes.
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* Makes sure there's room for an extra NULL byte at the end of the
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* buffer in case it holds a string.
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*/
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#define BufExpand(bp,nb) \
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if (((bp)->size - ((bp)->inPtr - (bp)->buffer)) < (nb)+1) {\
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int newSize = (bp)->size + max((nb)+1,BUF_ADD_INC); \
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Byte *newBuf = (Byte *) realloc((bp)->buffer, newSize); \
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\
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(bp)->inPtr = newBuf + ((bp)->inPtr - (bp)->buffer); \
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(bp)->outPtr = newBuf + ((bp)->outPtr - (bp)->buffer);\
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(bp)->buffer = newBuf;\
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(bp)->size = newSize;\
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}
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#define BUF_DEF_SIZE 256 /* Default buffer size */
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#define BUF_ADD_INC 256 /* Expansion increment when Adding */
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#define BUF_UNGET_INC 16 /* Expansion increment when Ungetting */
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/*-
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*-----------------------------------------------------------------------
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* Buf_AddByte --
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* Add a single byte to the buffer.
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*
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* Results:
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* None.
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*
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* Side Effects:
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* The buffer may be expanded.
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*
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*-----------------------------------------------------------------------
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*/
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void
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Buf_AddByte (buf, byte)
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Buffer buf;
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Byte byte;
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{
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register BufPtr bp = (BufPtr) buf;
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BufExpand (bp, 1);
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*bp->inPtr = byte;
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bp->inPtr += 1;
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/*
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* Null-terminate
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*/
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*bp->inPtr = 0;
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}
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/*-
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*-----------------------------------------------------------------------
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* Buf_AddBytes --
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* Add a number of bytes to the buffer.
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*
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* Results:
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* None.
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*
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* Side Effects:
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* Guess what?
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*
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*-----------------------------------------------------------------------
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*/
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void
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Buf_AddBytes (buf, numBytes, bytesPtr)
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Buffer buf;
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int numBytes;
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Byte *bytesPtr;
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{
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register BufPtr bp = (BufPtr) buf;
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BufExpand (bp, numBytes);
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bcopy (bytesPtr, bp->inPtr, numBytes);
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bp->inPtr += numBytes;
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/*
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* Null-terminate
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*/
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*bp->inPtr = 0;
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}
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/*-
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*-----------------------------------------------------------------------
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* Buf_UngetByte --
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* Place the byte back at the beginning of the buffer.
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*
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* Results:
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* SUCCESS if the byte was added ok. FAILURE if not.
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*
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* Side Effects:
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* The byte is stuffed in the buffer and outPtr is decremented.
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*
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*-----------------------------------------------------------------------
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*/
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void
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Buf_UngetByte (buf, byte)
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Buffer buf;
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Byte byte;
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{
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register BufPtr bp = (BufPtr) buf;
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if (bp->outPtr != bp->buffer) {
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bp->outPtr -= 1;
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*bp->outPtr = byte;
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} else if (bp->outPtr == bp->inPtr) {
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*bp->inPtr = byte;
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bp->inPtr += 1;
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*bp->inPtr = 0;
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} else {
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/*
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* Yech. have to expand the buffer to stuff this thing in.
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* We use a different expansion constant because people don't
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* usually push back many bytes when they're doing it a byte at
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* a time...
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*/
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int numBytes = bp->inPtr - bp->outPtr;
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Byte *newBuf;
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newBuf = (Byte *) malloc (bp->size + BUF_UNGET_INC);
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bcopy ((Address)bp->outPtr,
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(Address)(newBuf+BUF_UNGET_INC), numBytes+1);
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bp->outPtr = newBuf + BUF_UNGET_INC;
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bp->inPtr = bp->outPtr + numBytes;
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free ((Address)bp->buffer);
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bp->buffer = newBuf;
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bp->size += BUF_UNGET_INC;
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bp->outPtr -= 1;
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*bp->outPtr = byte;
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}
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}
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/*-
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*-----------------------------------------------------------------------
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* Buf_UngetBytes --
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* Push back a series of bytes at the beginning of the buffer.
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*
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* Results:
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* None.
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*
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* Side Effects:
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* outPtr is decremented and the bytes copied into the buffer.
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*
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*-----------------------------------------------------------------------
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*/
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void
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Buf_UngetBytes (buf, numBytes, bytesPtr)
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Buffer buf;
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int numBytes;
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Byte *bytesPtr;
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{
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register BufPtr bp = (BufPtr) buf;
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if (bp->outPtr - bp->buffer >= numBytes) {
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bp->outPtr -= numBytes;
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bcopy (bytesPtr, bp->outPtr, numBytes);
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} else if (bp->outPtr == bp->inPtr) {
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Buf_AddBytes (buf, numBytes, bytesPtr);
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} else {
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int curNumBytes = bp->inPtr - bp->outPtr;
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Byte *newBuf;
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int newBytes = max(numBytes,BUF_UNGET_INC);
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newBuf = (Byte *) malloc (bp->size + newBytes);
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bcopy((Address)bp->outPtr, (Address)(newBuf+newBytes), curNumBytes+1);
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bp->outPtr = newBuf + newBytes;
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bp->inPtr = bp->outPtr + curNumBytes;
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free ((Address)bp->buffer);
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bp->buffer = newBuf;
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bp->size += newBytes;
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bp->outPtr -= numBytes;
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bcopy ((Address)bytesPtr, (Address)bp->outPtr, numBytes);
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}
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}
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/*-
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*-----------------------------------------------------------------------
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* Buf_GetByte --
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* Return the next byte from the buffer. Actually returns an integer.
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*
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* Results:
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* Returns BUF_ERROR if there's no byte in the buffer, or the byte
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* itself if there is one.
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*
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* Side Effects:
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* outPtr is incremented and both outPtr and inPtr will be reset if
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* the buffer is emptied.
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*
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*-----------------------------------------------------------------------
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*/
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int
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Buf_GetByte (buf)
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Buffer buf;
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{
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BufPtr bp = (BufPtr) buf;
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int res;
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if (bp->inPtr == bp->outPtr) {
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return (BUF_ERROR);
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} else {
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res = (int) *bp->outPtr;
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bp->outPtr += 1;
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if (bp->outPtr == bp->inPtr) {
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bp->outPtr = bp->inPtr = bp->buffer;
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bp->inPtr = 0;
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}
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return (res);
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}
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}
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/*-
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*-----------------------------------------------------------------------
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* Buf_GetBytes --
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* Extract a number of bytes from the buffer.
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*
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* Results:
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* The number of bytes gotten.
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*
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* Side Effects:
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* The passed array is overwritten.
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*
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*-----------------------------------------------------------------------
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*/
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int
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Buf_GetBytes (buf, numBytes, bytesPtr)
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Buffer buf;
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int numBytes;
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Byte *bytesPtr;
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{
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BufPtr bp = (BufPtr) buf;
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if (bp->inPtr - bp->outPtr < numBytes) {
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numBytes = bp->inPtr - bp->outPtr;
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}
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bcopy (bp->outPtr, bytesPtr, numBytes);
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bp->outPtr += numBytes;
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if (bp->outPtr == bp->inPtr) {
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bp->outPtr = bp->inPtr = bp->buffer;
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*bp->inPtr = 0;
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}
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return (numBytes);
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}
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/*-
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*-----------------------------------------------------------------------
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* Buf_GetAll --
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* Get all the available data at once.
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*
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* Results:
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* A pointer to the data and the number of bytes available.
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*
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* Side Effects:
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* None.
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*
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*-----------------------------------------------------------------------
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*/
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Byte *
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Buf_GetAll (buf, numBytesPtr)
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Buffer buf;
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int *numBytesPtr;
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{
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BufPtr bp = (BufPtr)buf;
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if (numBytesPtr != (int *)NULL) {
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*numBytesPtr = bp->inPtr - bp->outPtr;
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}
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return (bp->outPtr);
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}
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/*-
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*-----------------------------------------------------------------------
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* Buf_Discard --
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* Throw away bytes in a buffer.
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*
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* Results:
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* None.
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*
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* Side Effects:
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* The bytes are discarded.
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*
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*-----------------------------------------------------------------------
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*/
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void
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Buf_Discard (buf, numBytes)
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Buffer buf;
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int numBytes;
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{
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register BufPtr bp = (BufPtr) buf;
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if (bp->inPtr - bp->outPtr <= numBytes) {
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bp->inPtr = bp->outPtr = bp->buffer;
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*bp->inPtr = 0;
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} else {
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bp->outPtr += numBytes;
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}
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}
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/*-
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*-----------------------------------------------------------------------
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* Buf_Size --
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* Returns the number of bytes in the given buffer. Doesn't include
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* the null-terminating byte.
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*
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* Results:
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* The number of bytes.
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*
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* Side Effects:
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* None.
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*
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*-----------------------------------------------------------------------
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*/
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int
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Buf_Size (buf)
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Buffer buf;
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{
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return (((BufPtr)buf)->inPtr - ((BufPtr)buf)->outPtr);
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}
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/*-
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*-----------------------------------------------------------------------
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* Buf_Init --
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* Initialize a buffer. If no initial size is given, a reasonable
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* default is used.
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*
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* Results:
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* A buffer to be given to other functions in this library.
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*
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* Side Effects:
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* The buffer is created, the space allocated and pointers
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* initialized.
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*
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*-----------------------------------------------------------------------
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*/
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Buffer
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Buf_Init (size)
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int size; /* Initial size for the buffer */
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{
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BufPtr bp; /* New Buffer */
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bp = (Buf *) malloc(sizeof(Buf));
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if (size <= 0) {
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size = BUF_DEF_SIZE;
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}
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bp->size = size;
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bp->buffer = (Byte *) malloc (size);
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bp->inPtr = bp->outPtr = bp->buffer;
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*bp->inPtr = 0;
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return ((Buffer) bp);
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}
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/*-
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*-----------------------------------------------------------------------
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* Buf_Destroy --
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* Nuke a buffer and all its resources.
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*
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* Results:
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* None.
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*
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* Side Effects:
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* The buffer is freed.
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*
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*-----------------------------------------------------------------------
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*/
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void
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Buf_Destroy (buf, freeData)
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Buffer buf; /* Buffer to destroy */
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Boolean freeData; /* TRUE if the data should be destroyed as well */
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{
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BufPtr bp = (BufPtr) buf;
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if (freeData) {
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free ((Address)bp->buffer);
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}
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free ((Address)bp);
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}
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