* Copyright 2004-2008, François Revol, <revol@free.fr>.
* Distributed under the terms of the MIT License.
*/
#define _BUILDING_fs 1
#include <sys/param.h>
#ifndef TEST_RB
#include "websearchfs.h"
#endif
#ifdef TEST_RB
#include <OS.h>
struct ring_buffer {
size_t size;
size_t current;
size_t avail;
unsigned char data[0];
};
#define ASSERT(op) if (!(op)) debugger("ASSERT: " #op " in " __FILE__ ":" __FUNCTION__)
#else
#define ASSERT(op) if (!(op)) panic("ASSERT: %s in %s:%s", #op, __FILE__, __FUNCTION__)
#endif
void rb_init(struct ring_buffer *rb, size_t size)
{
rb->size = size;
rb->current = 0;
rb->avail = 0;
}
void rb_clear(struct ring_buffer *rb)
{
rb->avail = 0;
rb->current = 0;
}
size_t rb_can_write(struct ring_buffer *rb)
{
if (!rb)
return 0;
return (rb->size - rb->avail);
}
size_t rb_can_read(struct ring_buffer *rb)
{
if (!rb)
return 0;
return rb->avail;
}
size_t rb_write(struct ring_buffer *rb, void *data, size_t len)
{
size_t index, towrite, written;
if (!rb)
return 0;
index = (rb->current + rb->avail) % rb->size;
towrite = rb_can_write(rb);
towrite = MIN(len, towrite);
if (towrite < 1)
return 0;
len = rb->size - index;
len = MIN(len, towrite);
memcpy(((char *)rb->data)+index, data, len);
rb->avail += len;
written = len;
if (len < towrite) {
towrite -= len;
len = MIN(towrite, rb_can_write(rb));
index = 0;
memcpy(((char *)rb->data)+index, ((char *)data)+written, len);
rb->avail += len;
written += len;
}
ASSERT(rb->avail <= rb->size);
return written;
}
size_t rb_read(struct ring_buffer *rb, void *data, size_t len)
{
size_t index, toread, got;
if (!rb)
return 0;
index = rb->current;
toread = rb_can_read(rb);
toread = MIN(len, toread);
if (toread < 1)
return 0;
len = rb->size - index;
len = MIN(len, toread);
memcpy(data, ((char *)rb->data)+index, len);
rb->avail -= len;
rb->current += len;
got = len;
if (len < toread) {
toread -= len;
len = MIN(toread, rb_can_read(rb));
index = 0;
memcpy(((char *)data)+got, ((char *)rb->data)+index, len);
rb->current = len;
rb->avail -= len;
got += len;
}
ASSERT(rb->avail <= rb->size);
return got;
}
#ifdef TEST_RB
int main(void)
{
struct _myrb {
struct ring_buffer rb;
char buff[10];
} myrb;
char buffer[10];
char obuffer[10];
int got, tow;
rb_init(&myrb.rb, 10);
while ((got = read(0, buffer, 10))) {
int len, olen;
len = rb_write(&myrb.rb, buffer, got);
olen = rb_read(&myrb.rb, obuffer, 10);
write(1, obuffer, olen);
}
return 1;
}
#endif
