Nyaaori/rockbox
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

Add some const keywords, improve some comments, add a safety check or two, should have no functional difference

Browse source 
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@15326 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Brandon Low 2007-10-27 01:37:33 +00:00
parent d08131a117
commit 404c6fbdb2
1 changed files with 34 additions and 29 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

63
apps/buffering.c
View file

@ -94,31 +94,31 @@
/* Ring buffer helper macros */
/* Buffer pointer (p) plus value (v), wrapped if necessary */
#define RINGBUF_ADD(p,v) ((p+v)<buffer_len ? p+v : p+v-buffer_len)
#define RINGBUF_ADD(p,v) (((p)+(v))<buffer_len ? (p)+(v) : (p)+(v)-buffer_len)
/* Buffer pointer (p) minus value (v), wrapped if necessary */
#define RINGBUF_SUB(p,v) ((p>=v) ? p-v : p+buffer_len-v)
#define RINGBUF_SUB(p,v) ((p>=v) ? (p)-(v) : (p)+buffer_len-(v))
/* How far value (v) plus buffer pointer (p1) will cross buffer pointer (p2) */
#define RINGBUF_ADD_CROSS(p1,v,p2) \
((p1<p2) ? (int)(p1+v)-(int)p2 : (int)(p1+v-p2)-(int)buffer_len)
((p1<p2) ? (int)((p1)+(v))-(int)(p2) : (int)((p1)+(v)-(p2))-(int)buffer_len)
/* Bytes available in the buffer */
#define BUF_USED RINGBUF_SUB(buf_widx, buf_ridx)
/* assert(sizeof(struct memory_handle)%4==0) */
struct memory_handle {
int id; /* A unique ID for the handle */
enum data_type type;
char path[MAX_PATH];
int fd;
size_t data; /* Start index of the handle's data buffer */
volatile size_t ridx; /* Current read pointer, relative to the main buffer */
size_t widx; /* Current write pointer */
size_t filesize; /* File total length */
size_t filerem; /* Remaining bytes of file NOT in buffer */
volatile size_t available; /* Available bytes to read from buffer */
size_t offset; /* Offset at which we started reading the file */
enum data_type type; /* Type of data buffered with this handle */
char path[MAX_PATH]; /* Path if data originated in a file */
int fd; /* File descriptor to path (-1 if closed) */
size_t data; /* Start index of the handle's data buffer */
volatile size_t ridx; /* Read pointer, relative to the main buffer */
size_t widx; /* Write pointer */
size_t filesize; /* File total length */
size_t filerem; /* Remaining bytes of file NOT in buffer */
volatile size_t available; /* Available bytes to read from buffer */
size_t offset; /* Offset at which we started reading the file */
struct memory_handle *next;
};
/* at all times, we have: filesize == offset + available + filerem */
/* invariant: filesize == offset + available + filerem */
static char *buffer;
static char *guard_buffer;
@ -131,8 +131,10 @@ static volatile size_t buf_ridx; /* current reading position */
/* Configuration */
static size_t conf_watermark = 0; /* Level to trigger filebuf fill */
static size_t conf_filechunk = 0; /* Largest chunk the codec accepts */
static size_t conf_preseek = 0; /* Codec pre-seek margin */
static size_t conf_filechunk = 0; /* Bytes-per-read for buffering (impacts
responsiveness of buffering thread) */
static size_t conf_preseek = 0; /* Distance a codec may look backwards after
seeking, to prevent double rebuffers */
#if MEM > 8
static size_t high_watermark = 0; /* High watermark for rebuffer */
#endif
@ -149,7 +151,7 @@ static int base_handle_id;
static struct mutex llist_mutex;
/* Handle cache (makes find_handle faster).
This needs be to be global so that move_handle can invalidate it. */
This is global so that move_handle and rm_handle can invalidate it. */
static struct memory_handle *cached_handle = NULL;
static buffer_low_callback buffer_low_callback_funcs[MAX_BUF_CALLBACKS];
@ -266,8 +268,11 @@ static struct memory_handle *add_handle(size_t *data_size)
/* Delete a given memory handle from the linked list
and return true for success. Nothing is actually erased from memory. */
static bool rm_handle(struct memory_handle *h)
static bool rm_handle(const struct memory_handle *h)
{
if (h == NULL)
return false;
mutex_lock(&llist_mutex);
if (h == first_handle) {
@ -275,7 +280,7 @@ static bool rm_handle(struct memory_handle *h)
if (h == cur_handle) {
/* h was the first and last handle: the buffer is now empty */
cur_handle = NULL;
buf_ridx = buf_widx;
buf_ridx = buf_widx = 0;
} else {
/* update buf_ridx to point to the new first handle */
buf_ridx = (void *)first_handle - (void *)buffer;
@ -285,7 +290,7 @@ static bool rm_handle(struct memory_handle *h)
while (m && m->next != h) {
m = m->next;
}
if (h && m && m->next == h) {
if (m && m->next == h) {
m->next = h->next;
if (h == cur_handle) {
cur_handle = m;
@ -309,7 +314,7 @@ static bool rm_handle(struct memory_handle *h)
/* Return a pointer to the memory handle of given ID.
NULL if the handle wasn't found */
static struct memory_handle *find_handle(int handle_id)
static struct memory_handle *find_handle(const int handle_id)
{
if (handle_id <= 0)
return NULL;
@ -336,9 +341,8 @@ static struct memory_handle *find_handle(int handle_id)
m = m->next;
}
/* This condition can only be reached with !m or m->id == handle_id */
if (m) {
if (m)
cached_handle = m;
}
mutex_unlock(&llist_mutex);
return m;
@ -853,7 +857,7 @@ int bufseek(int handle_id, size_t newpos)
Return 0 for success and < 0 for failure */
int bufadvance(int handle_id, off_t offset)
{
struct memory_handle *h = find_handle(handle_id);
const struct memory_handle *h = find_handle(handle_id);
if (!h)
return -1;
@ -865,7 +869,7 @@ int bufadvance(int handle_id, off_t offset)
Return the number of bytes copied or < 0 for failure. */
ssize_t bufread(int handle_id, size_t size, void *dest)
{
struct memory_handle *h = find_handle(handle_id);
const struct memory_handle *h = find_handle(handle_id);
if (!h)
return -1;
@ -908,7 +912,7 @@ ssize_t bufread(int handle_id, size_t size, void *dest)
The guard buffer may be used to provide the requested size */
ssize_t bufgetdata(int handle_id, size_t size, void **data)
{
struct memory_handle *h = find_handle(handle_id);
const struct memory_handle *h = find_handle(handle_id);
if (!h)
return -1;
@ -964,7 +968,7 @@ management functions for all the actual handle management work.
/* Get a handle offset from a pointer */
ssize_t buf_get_offset(int handle_id, void *ptr)
{
struct memory_handle *h = find_handle(handle_id);
const struct memory_handle *h = find_handle(handle_id);
if (!h)
return -1;
@ -973,7 +977,7 @@ ssize_t buf_get_offset(int handle_id, void *ptr)
ssize_t buf_handle_offset(int handle_id)
{
struct memory_handle *h = find_handle(handle_id);
const struct memory_handle *h = find_handle(handle_id);
if (!h)
return -1;
return h->offset;
@ -1142,6 +1146,7 @@ void buffering_thread(void)
data_counters.buffered < high_watermark)
{
fill_buffer();
update_data_counters();
}
if (ata_disk_is_active() && queue_empty(&buffering_queue) &&