ref: db8bfd2f8fd0dda83b71af2052dbe8b6d27c6c28
dir: /chunk.c/
#include <u.h>
#include <libc.h>
#include <thread.h>
#include "dat.h"
#include "fns.h"
/* chunk ≡ chain of chunks */
struct Buf{
uchar *buf;
usize bufsz;
Ref;
};
static Chunk *norris;
int
Δfmt(Fmt *fmt)
{
Dot *d;
d = va_arg(fmt->args, Dot*);
if(d == nil)
return fmtstrcpy(fmt, "[??:??:??:??]");
return fmtprint(fmt, "[from=%08zux cur=%08zux at=%08zux to=%08zux]",
d->from, d->pos, d->at, d->to);
}
int
χfmt(Fmt *fmt)
{
Chunk *c;
c = va_arg(fmt->args, Chunk*);
if(c == nil)
return fmtstrcpy(fmt, "[]");
return fmtprint(fmt, "0x%08p:%08zux::0x%08p:0x%08p", c, c->len, c->left, c->right);
}
static void
printchunks(Chunk *r)
{
usize len;
Chunk *c;
c = r;
len = 0;
do{
fprint(2, "\t%χ\toff=%08zux\n", c, len);
assert(c->right->left == c);
len += c->len;
c = c->right;
}while(c != r);
fprint(2, "\n");
}
void
dprint(Chunk *c, char *fmt, ...)
{
char s[256];
va_list arg;
if(!debug)
return;
va_start(arg, fmt);
vseprint(s, s+sizeof s, fmt, arg);
va_end(arg);
fprint(2, "%s", s);
printchunks(c == nil ? norris : c);
}
static Chunk *
newchunk(Buf *b)
{
Chunk *c;
c = emalloc(sizeof *c);
c->left = c;
c->right = c;
c->b = b;
c->off = 0;
c->len = b->bufsz;
incref(&b->Ref);
return c;
}
static Chunk *
newbuf(usize n)
{
Buf *b;
assert((n & 3) == 0);
b = emalloc(sizeof *b);
b->bufsz = n;
b->buf = emalloc(b->bufsz);
return newchunk(b);
}
static void
linkchunk(Chunk *left, Chunk *c)
{
c->left->right = left->right;
left->right->left = c->left;
c->left = left;
left->right = c;
}
static void
unlink(Chunk *left, Chunk *right)
{
left->left->right = right->right;
right->right->left = left->left;
left->left = right;
right->right = left;
}
static Chunk *
clonechunk(Chunk *c)
{
Chunk *nc;
assert(c != nil && c->b != nil);
nc = newchunk(c->b);
nc->off = c->off;
nc->len = c->len;
incref(c->b);
return nc;
}
Chunk *
clone(Chunk *left, Chunk *right)
{
Chunk *cl, *c, *nc;
cl = clonechunk(left);
c = cl;
for(; left!=right;){
left = left->right;
nc = clonechunk(left);
linkchunk(c, nc);
c = nc;
}
return cl;
}
static void
freebuf(Buf *b)
{
if(b == nil)
return;
free(b->buf);
free(b);
}
static void
freechunk(Chunk *c)
{
if(c == nil)
return;
if(c->b != nil && decref(c->b) == 0)
freebuf(c->b);
free(c);
}
void
freechain(Chunk *c)
{
Chunk *cl, *cp;
if(c == nil)
return;
for(cl=c->right; cl!=c; cl=cp){
cp = cl->right;
unlink(cl, cl);
freechunk(cl);
}
freechunk(c);
}
static void
shrinkbuf(Chunk *c, usize newsz)
{
Buf *b;
b = c->b;
assert(b != nil);
assert(newsz < b->bufsz && newsz > 0);
if(c->off + c->len > newsz)
c->len = newsz - c->off;
b->buf = erealloc(b->buf, newsz, b->bufsz);
}
usize
chunklen(Chunk *c)
{
usize n;
Chunk *cp;
for(cp=c, n=cp->len, cp=cp->right; cp!=c; cp=cp->right)
n += cp->len;
return n;
}
Chunk *
p2c(usize p, usize *off)
{
Chunk *c;
for(c=norris; p>=c->len; c=c->right){
if(c == norris->left){
assert(p == c->len);
break;
}
p -= c->len;
}
if(off != nil)
*off = p;
return c;
}
usize
c2p(Chunk *tc)
{
Chunk *c;
usize p;
for(p=0, c=norris; c!=tc; c=c->right)
p += c->len;
return p;
}
void
recalcsize(void)
{
int n;
n = c2p(norris->left) + norris->left->len;
if(dot.to == totalsz || dot.to > n)
dot.to = n;
if(dot.pos < dot.from || dot.pos > dot.to)
dot.pos = dot.from;
dot.at = -1ULL;
dprint(nil, "final %Δ\n", &dot);
totalsz = n;
}
#define ASSERT(x) {if(!(x)) printchunks(norris); assert((x)); }
void
paranoia(int exact)
{
usize n;
Chunk *c, *pc;
Buf *b;
ASSERT(dot.pos >= dot.from && dot.pos < dot.to);
for(pc=norris, n=pc->len, c=pc->right; c!=norris; pc=c, c=c->right){
b = c->b;
ASSERT(b != nil);
ASSERT((b->bufsz & 3) == 0 && b->bufsz >= Sampsz);
ASSERT(c->off < b->bufsz);
ASSERT(c->len > Sampsz);
ASSERT(c->off + c->len <= b->bufsz);
ASSERT(c->left == pc);
n += c->len;
}
if(exact){
ASSERT(n <= totalsz);
ASSERT(dot.to <= totalsz);
}
}
#undef ASSERT
void
setdot(Dot *dot, Chunk *right)
{
dot->from = 0;
if(right == nil)
dot->to = c2p(norris->left) + norris->left->len;
else
dot->to = c2p(right);
dot->at = -1ULL;
}
void
fixroot(Chunk *rc, usize off)
{
Chunk *c;
dprint(rc, "fixroot [%χ] %08zux\n", rc, off);
for(c=rc->left; off>0; off-=c->len, c=c->left){
if(off - c->len == 0)
break;
assert(off - c->len < off);
}
norris = c;
}
Chunk *
splitchunk(Chunk *c, usize off)
{
Chunk *nc;
dprint(nil, "splitchunk %Δ [%χ] off=%08zux\n", &dot, c, off);
if(off == 0 || c == norris->left && off == c->len)
return c;
assert(off <= c->len);
nc = clonechunk(c);
nc->off = c->off + off;
nc->len = c->len - off;
c->len = off;
linkchunk(c, nc);
return nc;
}
/* c1 [nc … c2] nc */
int
splitrange(usize from, usize to, Chunk **left, Chunk **right)
{
usize off;
Chunk *c;
dprint(nil, "splitrange from=%08zux to=%08zux\n", from, to);
c = p2c(from, &off);
if(off > 0){
splitchunk(c, off);
*left = c->right;
}else
*left = c; /* dangerous in combination with *right */
c = p2c(to, &off);
if(off < c->len - 1){
splitchunk(c, off);
*right = c;
}else
*right = c;
return 0;
}
Chunk *
cutrange(usize from, usize to, Chunk **latch)
{
Chunk *c, *left, *right;
dprint(nil, "cutrange from=%08zux to=%08zux\n", from, to);
if(splitrange(from, to, &left, &right) < 0)
return nil;
c = left->left;
if(left == norris)
norris = right->right;
unlink(left, right);
if(latch != nil)
*latch = left;
return c;
}
Chunk *
croprange(usize from, usize to, Chunk **latch)
{
Chunk *cut, *left, *right;
dprint(nil, "croprange from=%08zux to=%08zux\n", from, to);
if(splitrange(from, to, &left, &right) < 0)
return nil;
norris = left;
cut = right->right;
if(latch != nil)
*latch = cut;
unlink(right->right, left->left);
return left;
}
// FIXME: generalized insert(from, to), where from and to not necessarily distinct
Chunk *
inserton(usize from, usize to, Chunk *c, Chunk **latch)
{
Chunk *left;
dprint(c, "inserton from=%08zux to=%08zux\n", from, to);
left = cutrange(from, to, latch);
linkchunk(left, c);
dprint(nil, "done\n");
return left;
}
Chunk *
insertat(usize pos, Chunk *c)
{
usize off;
Chunk *left;
dprint(c, "insertat cur=%08zux\n", pos);
if(pos == 0){
left = norris->left;
norris = c;
}else{
left = p2c(pos, &off);
splitchunk(left, off);
}
if(off == 0)
left = left->left;
linkchunk(left, c);
return left;
}
uchar *
getslice(Dot *d, usize n, usize *sz)
{
usize Δbuf, Δloop, off;
Chunk *c;
if(d->pos >= totalsz){
werrstr("out of bounds");
*sz = 0;
return nil;
}
c = p2c(d->pos, &off);
Δloop = d->to - d->pos;
Δbuf = c->len - off;
if(n < Δloop && n < Δbuf){
*sz = n;
d->pos += n;
}else if(Δloop <= Δbuf){
*sz = Δloop;
d->pos = d->from;
}else{
*sz = Δbuf;
d->pos += Δbuf;
}
return c->b->buf + c->off + off;
}
Chunk *
readintochunks(int fd)
{
int n;
usize m;
Chunk *rc, *c, *nc;
for(m=0, rc=c=nil;; m+=n){
nc = newbuf(Iochunksz);
if(rc == nil)
rc = nc;
else
linkchunk(c, nc);
c = nc;
if((n = readn(fd, c->b->buf, Iochunksz)) < Iochunksz)
break;
yield();
}
close(fd);
if(n < 0)
fprint(2, "readintochunks: %r\n");
else if(n == 0){
if(c != rc)
unlink(c, c);
freechunk(c);
if(c == rc){
werrstr("readintochunks: nothing read");
return nil;
}
}else if(n > 0 && n < Iochunksz)
shrinkbuf(c, n);
return rc;
}
void
graphfrom(Chunk *c)
{
norris = c;
recalcsize();
setdot(&dot, nil);
}