Workshop o mikrokontrolérech na SKSP 2024.
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3 months ago
/*
* UCW Library -- Fast Buffered I/O on itself
*
* (c) 2012 Maria Matejka <mq@ucw.cz>
*
* This software may be freely distributed and used according to the terms
* of the GNU Lesser General Public License.
*/
#include <ucw/lib.h>
#include <ucw/clists.h>
#include <ucw/fastbuf.h>
#include <ucw/mempool.h>
#include <stdio.h>
#define FB_MULTI_NAME "<multi>"
struct fb_multi {
struct fastbuf fb;
struct mempool *mp;
struct subbuf *cur;
ucw_off_t len;
clist subbufs;
};
#define FB_MULTI(f) ((struct fb_multi *)(f))
struct subbuf {
cnode n;
ucw_off_t begin, end, offset;
struct fastbuf *fb;
};
static void
fbmulti_get_ptrs(struct fastbuf *f)
{
struct subbuf *sb = FB_MULTI(f)->cur;
struct fastbuf *ff = sb->fb;
f->buffer = ff->buffer;
f->bptr = ff->bptr;
f->bstop = ff->bstop;
f->bufend = ff->bufend;
f->pos = sb->begin + (ff->pos - sb->offset);
}
static void
fbmulti_set_ptrs(struct fastbuf *f)
{
FB_MULTI(f)->cur->fb->bptr = f->bptr;
}
static int
fbmulti_subbuf_next(struct fastbuf *f)
{
struct subbuf *cur = FB_MULTI(f)->cur;
struct subbuf *next = clist_next(&FB_MULTI(f)->subbufs, &cur->n);
if (!next)
return 0;
// Get the end of current buf if not known yet
if (!f->seek && !next->begin)
next->begin = cur->end = f->pos;
// Set the beginning of the next buf
if (next->fb->seek)
{
bsetpos(next->fb, 0);
next->offset = 0;
}
else
{
ASSERT(!f->seek);
next->offset = btell(next->fb);
}
// Set the pointers
FB_MULTI(f)->cur = next;
fbmulti_get_ptrs(f);
return 1;
}
static int
fbmulti_subbuf_prev(struct fastbuf *f)
{
// Called only when seeking, assuming everything seekable
struct subbuf *prev = clist_prev(&FB_MULTI(f)->subbufs, &FB_MULTI(f)->cur->n);
ASSERT(prev);
// Set pos to beginning, flush offset
bsetpos(prev->fb, 0);
prev->offset = 0;
// Set the pointers
FB_MULTI(f)->cur = prev;
fbmulti_get_ptrs(f);
return 1;
}
static int
fbmulti_refill(struct fastbuf *f)
{
fbmulti_set_ptrs(f);
// Refill the subbuf
uint len = FB_MULTI(f)->cur->fb->refill(FB_MULTI(f)->cur->fb);
if (len)
{
fbmulti_get_ptrs(f);
return len;
}
// Current buf returned EOF
// Take the next one if exists and redo
if (fbmulti_subbuf_next(f))
return fbmulti_refill(f);
else
return 0;
}
static int
fbmulti_seek(struct fastbuf *f, ucw_off_t pos, int whence)
{
fbmulti_set_ptrs(f);
switch(whence)
{
case SEEK_SET:
if (pos > FB_MULTI(f)->len)
bthrow(f, "seek", "Seek out of range");
while (pos > FB_MULTI(f)->cur->end) // Moving forward
{
int r = fbmulti_subbuf_next(f);
ASSERT(r);
}
while (pos < FB_MULTI(f)->cur->begin) // Moving backwards
{
int r = fbmulti_subbuf_prev(f);
ASSERT(r);
}
// Now cur is the right buffer.
FB_MULTI(f)->cur->fb->seek(FB_MULTI(f)->cur->fb, (pos - FB_MULTI(f)->cur->begin), SEEK_SET);
fbmulti_get_ptrs(f);
return 1;
case SEEK_END:
return fbmulti_seek(f, FB_MULTI(f)->len + pos, SEEK_SET);
default:
ASSERT(0);
}
}
static void
fbmulti_close(struct fastbuf *f)
{
CLIST_FOR_EACH(struct subbuf *, n, FB_MULTI(f)->subbufs)
bclose(n->fb);
mp_delete(FB_MULTI(f)->mp);
}
struct fastbuf *
fbmulti_create(void)
{
struct mempool *mp = mp_new(1024);
struct fastbuf *fb_out = mp_alloc_zero(mp, sizeof(struct fb_multi));
struct fb_multi *fbm = FB_MULTI(fb_out);
fbm->mp = mp;
fbm->len = 0;
clist_init(&fbm->subbufs);
fb_out->name = FB_MULTI_NAME;
fb_out->refill = fbmulti_refill;
fb_out->seek = fbmulti_seek;
fb_out->close = fbmulti_close;
return fb_out;
}
void
fbmulti_append(struct fastbuf *f, struct fastbuf *fb)
{
struct subbuf *last = clist_tail(&FB_MULTI(f)->subbufs);
struct subbuf *sb = mp_alloc(FB_MULTI(f)->mp, sizeof(*sb));
sb->fb = fb;
clist_add_tail(&FB_MULTI(f)->subbufs, &(sb->n));
ASSERT(fb->refill);
if (fb->seek)
{
if (f->seek)
{
sb->begin = last ? last->end : 0;
bseek(fb, 0, SEEK_END);
FB_MULTI(f)->len = sb->end = sb->begin + btell(fb);
}
bsetpos(fb, 0);
}
else
{
f->seek = NULL;
sb->offset = btell(fb);
sb->begin = 0;
sb->end = 0;
}
if (!last)
{
FB_MULTI(f)->cur = sb;
fbmulti_get_ptrs(f);
}
}
void
fbmulti_remove(struct fastbuf *f, struct fastbuf *fb)
{
bflush(f);
if (fb)
{
CLIST_FOR_EACH(struct subbuf *, n, FB_MULTI(f)->subbufs)
if (fb == n->fb)
{
clist_remove(&(n->n));
return;
}
die("Given fastbuf %p not in given fbmulti %p", fb, f);
}
else
clist_init(&FB_MULTI(f)->subbufs);
}
#ifdef TEST
int main(int argc, char **argv)
{
if (argc < 2)
{
fprintf(stderr, "You must specify a test (r, m, i, n)\n");
return 1;
}
switch (*argv[1])
{
case 'r':
{
char *data[] = { "One\nLine", "Two\nLines", "Th\nreeLi\nnes\n" };
struct fastbuf fb[ARRAY_SIZE(data)];
for (uint i=0;i<ARRAY_SIZE(data);i++)
fbbuf_init_read(&fb[i], data[i], strlen(data[i]), 0);
struct fastbuf *f = fbmulti_create();
fbmulti_append(f, &fb[0]);
fbmulti_append(f, &fb[1]);
fbmulti_append(f, &fb[2]);
char buffer[9];
while (bgets(f, buffer, 9))
puts(buffer);
bclose(f);
break;
}
case 'm':
{
char *data[] = { "Mnl", "ige" };
struct fastbuf fb[ARRAY_SIZE(data)];
for (uint i=0;i<ARRAY_SIZE(data);i++)
fbbuf_init_read(&fb[i], data[i], strlen(data[i]), 0);
struct fastbuf *f = fbmulti_create();
fbmulti_append(f, &fb[0]);
fbmulti_append(f, &fb[1]);
int pos[] = {0, 3, 1, 4, 2, 5};
for (uint i=0;i<ARRAY_SIZE(pos);i++)
{
bsetpos(f, pos[i]);
putchar(bgetc(f));
}
bclose(f);
break;
}
case 'i':
{
char *data = "Insae";
struct fastbuf fb[4];
fbbuf_init_read(&fb[0], data, 1, 0);
fbbuf_init_read(&fb[1], data + 1, 1, 0);
fbbuf_init_read(&fb[2], data + 2, 2, 0);
fbbuf_init_read(&fb[3], data + 4, 1, 0);
struct fastbuf *f = fbmulti_create();
fbmulti_append(f, &fb[0]);
fbmulti_append(f, &fb[1]);
fbmulti_append(f, &fb[2]);
fbmulti_append(f, &fb[1]);
fbmulti_append(f, &fb[3]);
char buffer[9];
while(bgets(f, buffer, 9))
puts(buffer);
bclose(f);
break;
}
case 'n':
{
char *data[] = { "Nested", "Data", "As", "In", "Real", "Usage", };
struct fastbuf fb[ARRAY_SIZE(data)];
for (uint i=0;i<ARRAY_SIZE(data);i++)
fbbuf_init_read(&fb[i], data[i], strlen(data[i]), 0);
struct fastbuf sp;
fbbuf_init_read(&sp, " ", 1, 0);
struct fastbuf nl;
fbbuf_init_read(&nl, "\n", 1, 0);
struct fastbuf *f = fbmulti_create();
struct fastbuf *ff;
ff = fbmulti_create();
fbmulti_append(ff, &fb[0]);
fbmulti_append(ff, &sp);
fbmulti_append(ff, &fb[1]);
fbmulti_append(f, ff);
fbmulti_append(f, &nl);
ff = fbmulti_create();
fbmulti_append(ff, &fb[2]);
fbmulti_append(ff, &sp);
fbmulti_append(ff, &fb[3]);
fbmulti_append(f, ff);
fbmulti_append(f, &nl);
ff = fbmulti_create();
fbmulti_append(ff, &fb[4]);
fbmulti_append(ff, &sp);
fbmulti_append(ff, &fb[5]);
fbmulti_append(f, ff);
fbmulti_append(f, &nl);
char buffer[20];
while (bgets(f, buffer, 20))
puts(buffer);
bclose(f);
break;
}
}
return 0;
}
#endif