freebsd-dev/sys/kern/subr_clist.c
Ed Schouten 89d647cb30 Remove a stale comment from the clists code.
We don't support quote bits.
2009-02-09 11:27:56 +00:00

465 lines
10 KiB
C

/*-
* Copyright (c) 1994, David Greenman
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice unmodified, this list of conditions, and the following
* disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*
* clist support routines
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/clist.h>
static MALLOC_DEFINE(M_CLIST, "clist", "clist queue blocks");
static struct cblock *cfreelist = NULL;
static struct cblock *cblock_alloc(void);
static void cblock_alloc_cblocks(int number);
static void cblock_free(struct cblock *cblockp);
static void cblock_free_cblocks(int number);
/*
* Remove a cblock from the cfreelist queue and return a pointer
* to it.
*/
static __inline struct cblock *
cblock_alloc(void)
{
struct cblock *cblockp;
cblockp = cfreelist;
if (cblockp == NULL)
panic("clist reservation botch");
cfreelist = cblockp->c_next;
cblockp->c_next = NULL;
return (cblockp);
}
/*
* Add a cblock to the cfreelist queue.
*/
static __inline void
cblock_free(struct cblock *cblockp)
{
cblockp->c_next = cfreelist;
cfreelist = cblockp;
}
/*
* Allocate some cblocks for the cfreelist queue.
*/
static void
cblock_alloc_cblocks(int number)
{
int i;
struct cblock *cbp;
for (i = 0; i < number; ++i) {
cbp = malloc(sizeof *cbp, M_CLIST, M_WAITOK);
cblock_free(cbp);
}
}
/*
* Set the cblock allocation policy for a clist.
* Must be called in process context at spltty().
*/
void
clist_alloc_cblocks(struct clist *clistp, int ccmax, int ccreserved)
{
int dcbr;
/*
* Allow for wasted space at the head.
*/
if (ccmax != 0)
ccmax += CBSIZE - 1;
if (ccreserved != 0)
ccreserved += CBSIZE - 1;
clistp->c_cbmax = roundup(ccmax, CBSIZE) / CBSIZE;
dcbr = roundup(ccreserved, CBSIZE) / CBSIZE - clistp->c_cbreserved;
if (dcbr >= 0)
cblock_alloc_cblocks(dcbr);
else {
if (clistp->c_cbreserved + dcbr < clistp->c_cbcount)
dcbr = clistp->c_cbcount - clistp->c_cbreserved;
cblock_free_cblocks(-dcbr);
}
clistp->c_cbreserved += dcbr;
}
/*
* Free some cblocks from the cfreelist queue back to the
* system malloc pool.
*/
static void
cblock_free_cblocks(int number)
{
int i;
for (i = 0; i < number; ++i)
free(cblock_alloc(), M_CLIST);
}
/*
* Free the cblocks reserved for a clist.
* Must be called at spltty().
*/
void
clist_free_cblocks(struct clist *clistp)
{
if (clistp->c_cbcount != 0)
panic("freeing active clist cblocks");
cblock_free_cblocks(clistp->c_cbreserved);
clistp->c_cbmax = 0;
clistp->c_cbreserved = 0;
}
/*
* Get a character from the head of a clist.
*/
int
getc(struct clist *clistp)
{
int chr = -1;
int s;
struct cblock *cblockp;
s = spltty();
/* If there are characters in the list, get one */
if (clistp->c_cc) {
cblockp = (struct cblock *)((intptr_t)clistp->c_cf & ~CROUND);
chr = (u_char)*clistp->c_cf;
/*
* Advance to next character.
*/
clistp->c_cf++;
clistp->c_cc--;
/*
* If we have advanced the 'first' character pointer
* past the end of this cblock, advance to the next one.
* If there are no more characters, set the first and
* last pointers to NULL. In either case, free the
* current cblock.
*/
if ((clistp->c_cf >= (char *)(cblockp+1)) || (clistp->c_cc == 0)) {
if (clistp->c_cc > 0) {
clistp->c_cf = cblockp->c_next->c_info;
} else {
clistp->c_cf = clistp->c_cl = NULL;
}
cblock_free(cblockp);
--clistp->c_cbcount;
}
}
splx(s);
return (chr);
}
/*
* Copy 'amount' of chars, beginning at head of clist 'clistp' to
* destination linear buffer 'dest'. Return number of characters
* actually copied.
*/
int
q_to_b(struct clist *clistp, char *dest, int amount)
{
struct cblock *cblockp;
struct cblock *cblockn;
char *dest_orig = dest;
int numc;
int s;
s = spltty();
while (clistp && amount && (clistp->c_cc > 0)) {
cblockp = (struct cblock *)((intptr_t)clistp->c_cf & ~CROUND);
cblockn = cblockp + 1; /* pointer arithmetic! */
numc = min(amount, (char *)cblockn - clistp->c_cf);
numc = min(numc, clistp->c_cc);
bcopy(clistp->c_cf, dest, numc);
amount -= numc;
clistp->c_cf += numc;
clistp->c_cc -= numc;
dest += numc;
/*
* If this cblock has been emptied, advance to the next
* one. If there are no more characters, set the first
* and last pointer to NULL. In either case, free the
* current cblock.
*/
if ((clistp->c_cf >= (char *)cblockn) || (clistp->c_cc == 0)) {
if (clistp->c_cc > 0) {
clistp->c_cf = cblockp->c_next->c_info;
} else {
clistp->c_cf = clistp->c_cl = NULL;
}
cblock_free(cblockp);
--clistp->c_cbcount;
}
}
splx(s);
return (dest - dest_orig);
}
/*
* Flush 'amount' of chars, beginning at head of clist 'clistp'.
*/
void
ndflush(struct clist *clistp, int amount)
{
struct cblock *cblockp;
struct cblock *cblockn;
int numc;
int s;
s = spltty();
while (amount && (clistp->c_cc > 0)) {
cblockp = (struct cblock *)((intptr_t)clistp->c_cf & ~CROUND);
cblockn = cblockp + 1; /* pointer arithmetic! */
numc = min(amount, (char *)cblockn - clistp->c_cf);
numc = min(numc, clistp->c_cc);
amount -= numc;
clistp->c_cf += numc;
clistp->c_cc -= numc;
/*
* If this cblock has been emptied, advance to the next
* one. If there are no more characters, set the first
* and last pointer to NULL. In either case, free the
* current cblock.
*/
if ((clistp->c_cf >= (char *)cblockn) || (clistp->c_cc == 0)) {
if (clistp->c_cc > 0) {
clistp->c_cf = cblockp->c_next->c_info;
} else {
clistp->c_cf = clistp->c_cl = NULL;
}
cblock_free(cblockp);
--clistp->c_cbcount;
}
}
splx(s);
}
/*
* Add a character to the end of a clist. Return -1 is no
* more clists, or 0 for success.
*/
int
putc(char chr, struct clist *clistp)
{
struct cblock *cblockp;
int s;
s = spltty();
if (clistp->c_cl == NULL) {
if (clistp->c_cbreserved < 1) {
splx(s);
printf("putc to a clist with no reserved cblocks\n");
return (-1); /* nothing done */
}
cblockp = cblock_alloc();
clistp->c_cbcount = 1;
clistp->c_cf = clistp->c_cl = cblockp->c_info;
clistp->c_cc = 0;
} else {
cblockp = (struct cblock *)((intptr_t)clistp->c_cl & ~CROUND);
if (((intptr_t)clistp->c_cl & CROUND) == 0) {
struct cblock *prev = (cblockp - 1);
if (clistp->c_cbcount >= clistp->c_cbreserved) {
splx(s);
return (-1);
}
cblockp = cblock_alloc();
clistp->c_cbcount++;
prev->c_next = cblockp;
clistp->c_cl = cblockp->c_info;
}
}
*clistp->c_cl++ = chr;
clistp->c_cc++;
splx(s);
return (0);
}
/*
* Copy data from linear buffer to clist chain. Return the
* number of characters not copied.
*/
int
b_to_q(char *src, int amount, struct clist *clistp)
{
struct cblock *cblockp;
int numc, s;
/*
* Avoid allocating an initial cblock and then not using it.
* c_cc == 0 must imply c_cbount == 0.
*/
if (amount <= 0)
return (amount);
s = spltty();
/*
* If there are no cblocks assigned to this clist yet,
* then get one.
*/
if (clistp->c_cl == NULL) {
if (clistp->c_cbreserved < 1) {
splx(s);
printf("b_to_q to a clist with no reserved cblocks.\n");
return (amount); /* nothing done */
}
cblockp = cblock_alloc();
clistp->c_cbcount = 1;
clistp->c_cf = clistp->c_cl = cblockp->c_info;
clistp->c_cc = 0;
} else {
cblockp = (struct cblock *)((intptr_t)clistp->c_cl & ~CROUND);
}
while (amount) {
/*
* Get another cblock if needed.
*/
if (((intptr_t)clistp->c_cl & CROUND) == 0) {
struct cblock *prev = cblockp - 1;
if (clistp->c_cbcount >= clistp->c_cbreserved) {
splx(s);
return (amount);
}
cblockp = cblock_alloc();
clistp->c_cbcount++;
prev->c_next = cblockp;
clistp->c_cl = cblockp->c_info;
}
/*
* Copy a chunk of the linear buffer up to the end
* of this cblock.
*/
numc = min(amount, (char *)(cblockp + 1) - clistp->c_cl);
bcopy(src, clistp->c_cl, numc);
/*
* ...and update pointer for the next chunk.
*/
src += numc;
clistp->c_cl += numc;
clistp->c_cc += numc;
amount -= numc;
/*
* If we go through the loop again, it's always
* for data in the next cblock, so by adding one (cblock),
* (which makes the pointer 1 beyond the end of this
* cblock) we prepare for the assignment of 'prev'
* above.
*/
cblockp += 1;
}
splx(s);
return (amount);
}
/*
* "Unput" a character from a clist.
*/
int
unputc(struct clist *clistp)
{
struct cblock *cblockp = NULL, *cbp = NULL;
int s;
int chr = -1;
s = spltty();
if (clistp->c_cc) {
--clistp->c_cc;
--clistp->c_cl;
chr = (u_char)*clistp->c_cl;
cblockp = (struct cblock *)((intptr_t)clistp->c_cl & ~CROUND);
/*
* If all of the characters have been unput in this
* cblock, then find the previous one and free this
* one.
*/
if (clistp->c_cc && (clistp->c_cl <= (char *)cblockp->c_info)) {
cbp = (struct cblock *)((intptr_t)clistp->c_cf & ~CROUND);
while (cbp->c_next != cblockp)
cbp = cbp->c_next;
/*
* When the previous cblock is at the end, the 'last'
* pointer always points (invalidly) one past.
*/
clistp->c_cl = (char *)(cbp+1);
cblock_free(cblockp);
--clistp->c_cbcount;
cbp->c_next = NULL;
}
}
/*
* If there are no more characters on the list, then
* free the last cblock.
*/
if ((clistp->c_cc == 0) && clistp->c_cl) {
cblockp = (struct cblock *)((intptr_t)clistp->c_cl & ~CROUND);
cblock_free(cblockp);
--clistp->c_cbcount;
clistp->c_cf = clistp->c_cl = NULL;
}
splx(s);
return (chr);
}