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Diffstat (limited to 'icedax/ringbuff.c')
| -rw-r--r-- | icedax/ringbuff.c | 231 |
1 files changed, 231 insertions, 0 deletions
diff --git a/icedax/ringbuff.c b/icedax/ringbuff.c new file mode 100644 index 0000000..6678ffb --- /dev/null +++ b/icedax/ringbuff.c @@ -0,0 +1,231 @@ +/* + * This file has been modified for the cdrkit suite. + * + * The behaviour and appearence of the program code below can differ to a major + * extent from the version distributed by the original author(s). + * + * For details, see Changelog file distributed with the cdrkit package. If you + * received this file from another source then ask the distributing person for + * a log of modifications. + * + */ + +/* @(#)ringbuff.c 1.8 02/11/21 Copyright 1998,1999,2000 Heiko Eissfeldt */ +#include "config.h" + +#include <stdxlib.h> +#include <stdio.h> +#include <standard.h> +#include <unixstd.h> + +#if defined(HAVE_SEMGET) && defined(USE_SEMAPHORES) +#include <sys/ipc.h> +#include <sys/sem.h> +#endif + +#include <usal/scsitransp.h> + +#include "mytype.h" +#include "global.h" +#include "interface.h" +#include "ringbuff.h" +#include "semshm.h" +#include "exitcodes.h" + +#undef WARN_INTERRUPT +#undef _DEBUG +#include <assert.h> + +static void occupy_buffer(void); + +myringbuff **he_fill_buffer; +myringbuff **last_buffer; +volatile unsigned long *total_segments_read; +volatile unsigned long *total_segments_written; +volatile int *child_waits; +volatile int *parent_waits; +volatile int *in_lendian; +volatile int *eorecording; + +static myringbuff *previous_read_buffer; +static unsigned int total_buffers; + +#define SEMS 2 + +#define defined_buffers() ((*total_segments_read) - (*total_segments_written)) +#define free_buffers() (total_buffers - defined_buffers()) +#define occupied_buffers() (defined_buffers()) + +/* ARGSUSED */ +void set_total_buffers(unsigned int num_buffers, int mysem_id) +{ +#if defined(HAVE_SEMGET) && defined(USE_SEMAPHORES) + union my_semun mysemun; + + mysemun.val = 0; + if (semctl(mysem_id,(int) DEF_SEM,SETVAL,mysemun) < 0) { + perror("semctl DEF_SEM"); + } + + mysemun.val = num_buffers; + if (semctl(mysem_id,(int) FREE_SEM,SETVAL,mysemun) < 0) { + perror("semctl FREE_SEM"); + } +#endif + + total_buffers = num_buffers; + + /* initialize pointers */ + *he_fill_buffer = *last_buffer = previous_read_buffer = NULL; +#ifdef DEBUG_SHM +fprintf(stderr, "init: fill_b = %p, last_b = %p\n", *he_fill_buffer, *last_buffer); +#endif +} + +const myringbuff *get_previous_read_buffer() +{ + assert(previous_read_buffer != NULL); + assert(previous_read_buffer != *he_fill_buffer); + return previous_read_buffer; +} + +const myringbuff *get_he_fill_buffer() +{ + assert(*he_fill_buffer != NULL); + assert(previous_read_buffer != *he_fill_buffer); + return *he_fill_buffer; +} + +void define_buffer() +{ + assert(defined_buffers() < total_buffers); + +#ifdef _DEBUG +#if 0 + fprintf(stderr,"stop reading %p - %p\n", + *he_fill_buffer, (char *)(*he_fill_buffer) + ENTRY_SIZE -1); +#endif +#endif + + if (*last_buffer == NULL) + *last_buffer = *he_fill_buffer; +#ifdef DEBUG_SHM +fprintf(stderr, "define: fill_b = %p, last_b = %p\n", *he_fill_buffer, *last_buffer); +#endif + + (*total_segments_read)++; + semrelease(sem_id,DEF_SEM,1); +} + +void drop_buffer() +{ + assert(free_buffers() < total_buffers); + assert(occupied_buffers() > 0); + +#ifdef _DEBUG +#if 0 + fprintf(stderr," stop writing %p - %p ", + *last_buffer, (char *)(*last_buffer) + ENTRY_SIZE -1); +#endif +#endif + + if (*last_buffer == NULL) + *last_buffer = *he_fill_buffer; + else + *last_buffer = INC(*last_buffer); +#ifdef DEBUG_SHM +fprintf(stderr, "drop: fill_b = %p, last_b = %p\n", *he_fill_buffer, *last_buffer); +#endif + (*total_segments_written)++; + semrelease(sem_id,FREE_SEM, 1); +} + +void drop_all_buffers() +{ + (*total_segments_written) = (*total_segments_read); + semrelease(sem_id,FREE_SEM, total_buffers); +} + +static void occupy_buffer() +{ + assert(occupied_buffers() <= total_buffers); + + previous_read_buffer = *he_fill_buffer; + + if (*he_fill_buffer == NULL) { + *he_fill_buffer = RB_BASE; + } else { + *he_fill_buffer = INC(*he_fill_buffer); + } +} + +#if defined HAVE_FORK_AND_SHAREDMEM +myringbuff * get_next_buffer() +{ +#ifdef WARN_INTERRUPT + if (free_buffers() <= 0) { + fprintf(stderr, "READER waits!! r=%lu, w=%lu\n", *total_segments_read, +*total_segments_written); + } +#endif + + /* wait for a new buffer to become available */ + if (semrequest(sem_id,FREE_SEM) != 0) { + /* semaphore operation failed. + try again... + */ + fprintf(stderr, "child reader sem request failed\n"); + exit(SEMAPHORE_ERROR); + } +#if 0 + fprintf(stderr,"start reading %p - %p\n", + *he_fill_buffer, (char *)(*fill_buffer) + ENTRY_SIZE -1); +#endif + + occupy_buffer(); + +#ifdef DEBUG_SHM +fprintf(stderr, "next: fill_b = %p, last_b = %p, @last = %p\n", *he_fill_buffer, *last_buffer, last_buffer); +#endif + return *he_fill_buffer; +} + +myringbuff *get_oldest_buffer() +{ + myringbuff *retval; + +#ifdef WARN_INTERRUPT + if (free_buffers() == total_buffers) { + fprintf(stderr, "WRITER waits!! r=%lu, w=%lu\n", *total_segments_read, + *total_segments_written); + } +#endif + /* wait for buffer to be defined */ + if (semrequest(sem_id,DEF_SEM) != 0) { + /* semaphore operation failed. */ + perror("request defined buff:"); + fprintf(stderr, "parent writer sem request failed\n"); + } + + retval = *last_buffer; + +#if 0 + fprintf(stderr," begin writing %p - %p\n", + retval, (char *)retval + ENTRY_SIZE -1); +#endif + + return retval; +} +#else /* HAVE_FORK_AND_SHAREDMEM */ +myringbuff * get_next_buffer() +{ + occupy_buffer(); + return *he_fill_buffer; +} + +myringbuff * get_oldest_buffer() +{ + return *he_fill_buffer; +} +#endif /* HAVE_FORK_AND_SHAREDMEM */ + |