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Aminet 5
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Aminet 5 - March 1995.iso
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amipeg04.lha
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aMiPEG_0.4
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util.c
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C/C++ Source or Header
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1994-04-22
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4KB
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202 lines
/*
* This file handles filling of the buffer and contains some additional utility routines.
*/
#include "video.h"
#include "proto.h"
#include "util.h"
/* Declarations of global variables used. */
int bitOffset;
int bufLength;
unsigned int *bitBuffer;
/*
*--------------------------------------------------------------
*
* correct_underflow --
*
* Called when buffer does not have sufficient data to
* satisfy request for bits.
* Calls get_more_data, an application specific routine
* required to fill the buffer with more data.
*
* Results:
* None really.
*
* Side effects:
* buf_length and buffer fields in curVidStream structure
* may be changed.
*
*--------------------------------------------------------------
*/
void correct_underflow(void)
{
int status;
status = get_more_data(curVidStream->buf_start, curVidStream->max_buf_length, &bufLength, &bitBuffer);
if (status < 0) {
if (!quietFlag) {
fprintf (stderr, "\n");
perror("Unexpected read error.");
}
exit(1);
}
else if ((status == 0) && (bufLength < 1)) {
if (!quietFlag) {
fprintf(stderr, "\nImproper or missing sequence end code.\n");
}
#ifdef ANALYSIS
PrintAllStats();
#endif
if (!quietFlag) {
PrintTimeInfo();
}
if (loopFlag) longjmp(env, 1);
DestroyVidStream(curVidStream);
exit(0);
}
}
/*
*--------------------------------------------------------------
*
* get_ext_data --
*
* Assumes that bit stream is at begining of extension
* data. Parses off extension data into dynamically
* allocated space until start code is hit.
*
* Results:
* Pointer to dynamically allocated memory containing
* extension data.
*
* Side effects:
* Bit stream irreversibly parsed.
*
* Niceness -10000 !!!!
*
*--------------------------------------------------------------
*/
char *get_ext_data (void)
{
int size, marker;
char *dataPtr;
unsigned int data;
/* Set initial ext data buffer size. */
size = EXT_BUF_SIZE;
/* Allocate ext data buffer. */
dataPtr = (char *) malloc(size);
/* Initialize marker to keep place in ext data buffer. */
marker = 0;
/* While next data is not start code... */
while ((show_bitsn(24,data)) != 0x000001) { /* data re-usage could be applied ! */
/* Put ext data into ext data buffer. Advance marker. */
get_bits8( dataPtr[marker] );
marker++;
/* If end of ext data buffer reached, resize data buffer. */
if (marker == size) {
size += EXT_BUF_SIZE;
dataPtr = (char *) realloc(dataPtr, size);
}
}
/* Realloc data buffer to free any extra space. */
dataPtr = (char *) realloc(dataPtr, marker);
/* Return pointer to ext data buffer. */
return dataPtr;
}
/*
*--------------------------------------------------------------
*
* get_extra_bit_info --
*
* Parses off extra bit info stream into dynamically
* allocated memory. Extra bit info is indicated by
* a flag bit set to 1, followed by 8 bits of data.
* This continues until the flag bit is zero. Assumes
* that bit stream set to first flag bit in extra
* bit info stream.
*
* Results:
* Pointer to dynamically allocated memory with extra
* bit info in it. Flag bits are NOT included.
*
* Side effects:
* Bit stream irreversibly parsed.
*
*--------------------------------------------------------------
*/
char *get_extra_bit_info (void)
{
int size, marker;
char *dataPtr;
unsigned int data;
/* Get first flag bit; if flag is false, return NULL pointer (i.e. no extra bit info). */
if (!(get_bits1(data))) return NULL;
/* Initialize size of extra bit info buffer and allocate. */
size = EXT_BUF_SIZE;
dataPtr = (char *) malloc(size);
/* Reset marker to hold place in buffer. */
marker = 0;
/* While flag bit is true. */
while (data) {
/* Place in extra bit info buffer. */
get_bits8( dataPtr[marker] );
marker++;
/* If buffer is full, reallocate. */
if (marker == size) {
size += EXT_BUF_SIZE;
dataPtr = (char *) realloc(dataPtr, size);
}
/* Get next flag bit. */
get_bits1(data);
}
/* Reallocate buffer to free extra space. */
dataPtr = (char *) realloc(dataPtr, marker);
/* Return pointer to extra bit info buffer. */
return dataPtr;
}