mirror of https://github.com/noisymime/Arduino.git
Cristian Maglie
parent
cce70d269c
commit
d457332664
|
|
@ -0,0 +1,380 @@
|
|||
/* Copyright (c) 2002, 2004, 2010 Joerg Wunsch
|
||||
Copyright (c) 2010 Gerben van den Broeke
|
||||
All rights reserved.
|
||||
|
||||
malloc, free, realloc from avr-libc 1.7.0
|
||||
with minor modifications, by Paul Stoffregen
|
||||
|
||||
Redistribution and use in source and binary forms, with or without
|
||||
modification, are permitted provided that the following conditions are met:
|
||||
|
||||
* Redistributions of source code must retain the above copyright
|
||||
notice, this list of conditions and the following disclaimer.
|
||||
|
||||
* 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.
|
||||
|
||||
* Neither the name of the copyright holders nor the names of
|
||||
contributors may be used to endorse or promote products derived
|
||||
from this software without specific prior written permission.
|
||||
|
||||
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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.
|
||||
*/
|
||||
|
||||
|
||||
#include <stdlib.h>
|
||||
#include <inttypes.h>
|
||||
#include <string.h>
|
||||
#include <avr/io.h>
|
||||
|
||||
|
||||
#define __MALLOC_MARGIN__ 120
|
||||
|
||||
|
||||
struct __freelist {
|
||||
size_t sz;
|
||||
struct __freelist *nx;
|
||||
};
|
||||
|
||||
/*
|
||||
* Exported interface:
|
||||
*
|
||||
* When extending the data segment, the allocator will not try to go
|
||||
* beyond the current stack limit, decreased by __malloc_margin bytes.
|
||||
* Thus, all possible stack frames of interrupt routines that could
|
||||
* interrupt the current function, plus all further nested function
|
||||
* calls must not require more stack space, or they'll risk to collide
|
||||
* with the data segment.
|
||||
*/
|
||||
|
||||
|
||||
#define STACK_POINTER() ((char *)AVR_STACK_POINTER_REG)
|
||||
extern char __heap_start;
|
||||
char *__brkval = &__heap_start; // first location not yet allocated
|
||||
struct __freelist *__flp; // freelist pointer (head of freelist)
|
||||
char *__brkval_maximum = 100;
|
||||
|
||||
void *
|
||||
malloc(size_t len)
|
||||
{
|
||||
struct __freelist *fp1, *fp2, *sfp1, *sfp2;
|
||||
char *cp;
|
||||
size_t s, avail;
|
||||
|
||||
/*
|
||||
* Our minimum chunk size is the size of a pointer (plus the
|
||||
* size of the "sz" field, but we don't need to account for
|
||||
* this), otherwise we could not possibly fit a freelist entry
|
||||
* into the chunk later.
|
||||
*/
|
||||
if (len < sizeof(struct __freelist) - sizeof(size_t))
|
||||
len = sizeof(struct __freelist) - sizeof(size_t);
|
||||
|
||||
/*
|
||||
* First, walk the free list and try finding a chunk that
|
||||
* would match exactly. If we found one, we are done. While
|
||||
* walking, note down the smallest chunk we found that would
|
||||
* still fit the request -- we need it for step 2.
|
||||
*
|
||||
*/
|
||||
for (s = 0, fp1 = __flp, fp2 = 0;
|
||||
fp1;
|
||||
fp2 = fp1, fp1 = fp1->nx) {
|
||||
if (fp1->sz < len)
|
||||
continue;
|
||||
if (fp1->sz == len) {
|
||||
/*
|
||||
* Found it. Disconnect the chunk from the
|
||||
* freelist, and return it.
|
||||
*/
|
||||
if (fp2)
|
||||
fp2->nx = fp1->nx;
|
||||
else
|
||||
__flp = fp1->nx;
|
||||
return &(fp1->nx);
|
||||
}
|
||||
else {
|
||||
if (s == 0 || fp1->sz < s) {
|
||||
/* this is the smallest chunk found so far */
|
||||
s = fp1->sz;
|
||||
sfp1 = fp1;
|
||||
sfp2 = fp2;
|
||||
}
|
||||
}
|
||||
}
|
||||
/*
|
||||
* Step 2: If we found a chunk on the freelist that would fit
|
||||
* (but was too large), look it up again and use it, since it
|
||||
* is our closest match now. Since the freelist entry needs
|
||||
* to be split into two entries then, watch out that the
|
||||
* difference between the requested size and the size of the
|
||||
* chunk found is large enough for another freelist entry; if
|
||||
* not, just enlarge the request size to what we have found,
|
||||
* and use the entire chunk.
|
||||
*/
|
||||
if (s) {
|
||||
if (s - len < sizeof(struct __freelist)) {
|
||||
/* Disconnect it from freelist and return it. */
|
||||
if (sfp2)
|
||||
sfp2->nx = sfp1->nx;
|
||||
else
|
||||
__flp = sfp1->nx;
|
||||
return &(sfp1->nx);
|
||||
}
|
||||
/*
|
||||
* Split them up. Note that we leave the first part
|
||||
* as the new (smaller) freelist entry, and return the
|
||||
* upper portion to the caller. This saves us the
|
||||
* work to fix up the freelist chain; we just need to
|
||||
* fixup the size of the current entry, and note down
|
||||
* the size of the new chunk before returning it to
|
||||
* the caller.
|
||||
*/
|
||||
cp = (char *)sfp1;
|
||||
s -= len;
|
||||
cp += s;
|
||||
sfp2 = (struct __freelist *)cp;
|
||||
sfp2->sz = len;
|
||||
sfp1->sz = s - sizeof(size_t);
|
||||
return &(sfp2->nx);
|
||||
}
|
||||
/*
|
||||
* Step 3: If the request could not be satisfied from a
|
||||
* freelist entry, just prepare a new chunk. This means we
|
||||
* need to obtain more memory first. The largest address just
|
||||
* not allocated so far is remembered in the brkval variable.
|
||||
* Under Unix, the "break value" was the end of the data
|
||||
* segment as dynamically requested from the operating system.
|
||||
* Since we don't have an operating system, just make sure
|
||||
* that we don't collide with the stack.
|
||||
*/
|
||||
cp = STACK_POINTER() - __MALLOC_MARGIN__;
|
||||
if (cp <= __brkval)
|
||||
/*
|
||||
* Memory exhausted.
|
||||
*/
|
||||
return 0;
|
||||
avail = cp - __brkval;
|
||||
/*
|
||||
* Both tests below are needed to catch the case len >= 0xfffe.
|
||||
*/
|
||||
if (avail >= len && avail >= len + sizeof(size_t)) {
|
||||
fp1 = (struct __freelist *)__brkval;
|
||||
__brkval += len + sizeof(size_t);
|
||||
__brkval_maximum = __brkval;
|
||||
fp1->sz = len;
|
||||
return &(fp1->nx);
|
||||
}
|
||||
/*
|
||||
* Step 4: There's no help, just fail. :-/
|
||||
*/
|
||||
return 0;
|
||||
}
|
||||
|
||||
|
||||
void
|
||||
free(void *p)
|
||||
{
|
||||
struct __freelist *fp1, *fp2, *fpnew;
|
||||
char *cp1, *cp2, *cpnew;
|
||||
|
||||
/* ISO C says free(NULL) must be a no-op */
|
||||
if (p == 0)
|
||||
return;
|
||||
|
||||
cpnew = p;
|
||||
cpnew -= sizeof(size_t);
|
||||
fpnew = (struct __freelist *)cpnew;
|
||||
fpnew->nx = 0;
|
||||
|
||||
/*
|
||||
* Trivial case first: if there's no freelist yet, our entry
|
||||
* will be the only one on it. If this is the last entry, we
|
||||
* can reduce __brkval instead.
|
||||
*/
|
||||
if (__flp == 0) {
|
||||
if ((char *)p + fpnew->sz == __brkval)
|
||||
__brkval = cpnew;
|
||||
else
|
||||
__flp = fpnew;
|
||||
return;
|
||||
}
|
||||
|
||||
/*
|
||||
* Now, find the position where our new entry belongs onto the
|
||||
* freelist. Try to aggregate the chunk with adjacent chunks
|
||||
* if possible.
|
||||
*/
|
||||
for (fp1 = __flp, fp2 = 0;
|
||||
fp1;
|
||||
fp2 = fp1, fp1 = fp1->nx) {
|
||||
if (fp1 < fpnew)
|
||||
continue;
|
||||
cp1 = (char *)fp1;
|
||||
fpnew->nx = fp1;
|
||||
if ((char *)&(fpnew->nx) + fpnew->sz == cp1) {
|
||||
/* upper chunk adjacent, assimilate it */
|
||||
fpnew->sz += fp1->sz + sizeof(size_t);
|
||||
fpnew->nx = fp1->nx;
|
||||
}
|
||||
if (fp2 == 0) {
|
||||
/* new head of freelist */
|
||||
__flp = fpnew;
|
||||
return;
|
||||
}
|
||||
break;
|
||||
}
|
||||
/*
|
||||
* Note that we get here either if we hit the "break" above,
|
||||
* or if we fell off the end of the loop. The latter means
|
||||
* we've got a new topmost chunk. Either way, try aggregating
|
||||
* with the lower chunk if possible.
|
||||
*/
|
||||
fp2->nx = fpnew;
|
||||
cp2 = (char *)&(fp2->nx);
|
||||
if (cp2 + fp2->sz == cpnew) {
|
||||
/* lower junk adjacent, merge */
|
||||
fp2->sz += fpnew->sz + sizeof(size_t);
|
||||
fp2->nx = fpnew->nx;
|
||||
}
|
||||
/*
|
||||
* If there's a new topmost chunk, lower __brkval instead.
|
||||
*/
|
||||
for (fp1 = __flp, fp2 = 0;
|
||||
fp1->nx != 0;
|
||||
fp2 = fp1, fp1 = fp1->nx)
|
||||
/* advance to entry just before end of list */;
|
||||
cp2 = (char *)&(fp1->nx);
|
||||
if (cp2 + fp1->sz == __brkval) {
|
||||
if (fp2 == NULL)
|
||||
/* Freelist is empty now. */
|
||||
__flp = NULL;
|
||||
else
|
||||
fp2->nx = NULL;
|
||||
__brkval = cp2 - sizeof(size_t);
|
||||
}
|
||||
}
|
||||
|
||||
|
||||
|
||||
void *
|
||||
realloc(void *ptr, size_t len)
|
||||
{
|
||||
struct __freelist *fp1, *fp2, *fp3, *ofp3;
|
||||
char *cp, *cp1;
|
||||
void *memp;
|
||||
size_t s, incr;
|
||||
|
||||
/* Trivial case, required by C standard. */
|
||||
if (ptr == 0)
|
||||
return malloc(len);
|
||||
|
||||
cp1 = (char *)ptr;
|
||||
cp1 -= sizeof(size_t);
|
||||
fp1 = (struct __freelist *)cp1;
|
||||
|
||||
cp = (char *)ptr + len; /* new next pointer */
|
||||
if (cp < cp1)
|
||||
/* Pointer wrapped across top of RAM, fail. */
|
||||
return 0;
|
||||
|
||||
/*
|
||||
* See whether we are growing or shrinking. When shrinking,
|
||||
* we split off a chunk for the released portion, and call
|
||||
* free() on it. Therefore, we can only shrink if the new
|
||||
* size is at least sizeof(struct __freelist) smaller than the
|
||||
* previous size.
|
||||
*/
|
||||
if (len <= fp1->sz) {
|
||||
/* The first test catches a possible unsigned int
|
||||
* rollover condition. */
|
||||
if (fp1->sz <= sizeof(struct __freelist) ||
|
||||
len > fp1->sz - sizeof(struct __freelist))
|
||||
return ptr;
|
||||
fp2 = (struct __freelist *)cp;
|
||||
fp2->sz = fp1->sz - len - sizeof(size_t);
|
||||
fp1->sz = len;
|
||||
free(&(fp2->nx));
|
||||
return ptr;
|
||||
}
|
||||
|
||||
/*
|
||||
* If we get here, we are growing. First, see whether there
|
||||
* is space in the free list on top of our current chunk.
|
||||
*/
|
||||
incr = len - fp1->sz;
|
||||
cp = (char *)ptr + fp1->sz;
|
||||
fp2 = (struct __freelist *)cp;
|
||||
for (s = 0, ofp3 = 0, fp3 = __flp;
|
||||
fp3;
|
||||
ofp3 = fp3, fp3 = fp3->nx) {
|
||||
if (fp3 == fp2 && fp3->sz + sizeof(size_t) >= incr) {
|
||||
/* found something that fits */
|
||||
if (fp3->sz + sizeof(size_t) - incr > sizeof(struct __freelist)) {
|
||||
/* split off a new freelist entry */
|
||||
cp = (char *)ptr + len;
|
||||
fp2 = (struct __freelist *)cp;
|
||||
fp2->nx = fp3->nx;
|
||||
fp2->sz = fp3->sz - incr;
|
||||
fp1->sz = len;
|
||||
} else {
|
||||
/* it just fits, so use it entirely */
|
||||
fp1->sz += fp3->sz + sizeof(size_t);
|
||||
fp2 = fp3->nx;
|
||||
}
|
||||
if (ofp3)
|
||||
ofp3->nx = fp2;
|
||||
else
|
||||
__flp = fp2;
|
||||
return ptr;
|
||||
}
|
||||
/*
|
||||
* Find the largest chunk on the freelist while
|
||||
* walking it.
|
||||
*/
|
||||
if (fp3->sz > s)
|
||||
s = fp3->sz;
|
||||
}
|
||||
/*
|
||||
* If we are the topmost chunk in memory, and there was no
|
||||
* large enough chunk on the freelist that could be re-used
|
||||
* (by a call to malloc() below), quickly extend the
|
||||
* allocation area if possible, without need to copy the old
|
||||
* data.
|
||||
*/
|
||||
if (__brkval == (char *)ptr + fp1->sz && len > s) {
|
||||
cp = (char *)ptr + len;
|
||||
cp1 = STACK_POINTER() - __MALLOC_MARGIN__;
|
||||
if (cp < cp1) {
|
||||
__brkval = cp;
|
||||
__brkval_maximum = cp;
|
||||
fp1->sz = len;
|
||||
return ptr;
|
||||
}
|
||||
/* If that failed, we are out of luck. */
|
||||
return 0;
|
||||
}
|
||||
|
||||
/*
|
||||
* Call malloc() for a new chunk, then copy over the data, and
|
||||
* release the old region.
|
||||
*/
|
||||
if ((memp = malloc(len)) == 0)
|
||||
return 0;
|
||||
memcpy(memp, ptr, fp1->sz);
|
||||
free(ptr);
|
||||
return memp;
|
||||
}
|
||||
|
||||
Loading…
Reference in New Issue