/* memory allocation routines
 * Copyright 1991 Phil Karn, KA9Q
 *
 * Adapted from alloc routine in K&R; memory statistics and interrupt
 * protection added for use with net package. Must be used in place of
 * standard Turbo-C library routines because the latter check for stack/heap
 * collisions. This causes erroneous failures because process stacks are
 * allocated off the heap.
 */

#include <stdio.h>
#include <dos.h>
#include <alloc.h>
#include "global.h"
#include "mbuf.h"
#include "proc.h"
#include "cmdparse.h"

static unsigned long Memfail;	/* Count of allocation failures */
static unsigned long Allocs;	/* Total allocations */
static unsigned long Frees;	/* Total frees */
static unsigned long Invalid;	/* Total calls to free with garbage arg */
static unsigned long Intalloc;	/* Calls to malloc with ints disabled */
static unsigned long Intfree;	/* Calls to free with ints disabled */
static int Memwait;		/* Number of tasks waiting for memory */
static unsigned long Yellows;	/* Yellow alert garbage collections */
static unsigned long Reds;	/* Red alert garbage collections */
unsigned long Availmem;		/* Heap memory, ABLKSIZE units */
static unsigned long Morecores;

static unsigned long Sizes[16];

static int dostat __ARGS((int argc,char *argv[],void *p));
static int dofreelist __ARGS((int argc,char *argv[],void *p));
static int doibufsize __ARGS((int argc,char *argv[],void *p));
static int donibufs __ARGS((int argc,char *argv[],void *p));
static int dothresh __ARGS((int argc,char *argv[],void *p));
static int dosizes __ARGS((int argc,char *argv[],void *p));

struct cmds Memcmds[] = {
	"freelist",	dofreelist,	0, 0, NULLCHAR,
	"ibufsize",	doibufsize,	0, 0, NULLCHAR,
	"nibufs",	donibufs,	0, 0, NULLCHAR,
	"sizes",	dosizes,	0, 0, NULLCHAR,
	"status",	dostat,		0, 0, NULLCHAR,
	"thresh",	dothresh,	0, 0, NULLCHAR,
	NULLCHAR,
};

#ifdef	LARGEDATA
#define	HUGE	huge
#else
#define	HUGE
#endif

union header {
	struct {
		union header HUGE *ptr;
		unsigned long size;
	} s;
	long l[2];
};

typedef union header HEADER;
#define	NULLHDR	(HEADER HUGE *)NULL

#define	ABLKSIZE	(sizeof (HEADER))

static HEADER HUGE *morecore __ARGS((unsigned nu));

static HEADER Base;
static HEADER HUGE *Allocp = NULLHDR;
static unsigned long Heapsize;

/* Allocate block of 'nb' bytes */
void *
malloc(nb)
unsigned nb;
{
	register HEADER HUGE *p, HUGE *q;
	register unsigned nu;
	int i;

	if(!istate())
		Intalloc++;
	if(nb == 0)
		return NULL;

	/* Record the size of this request */
	if((i = log2(nb)) >= 0)
		Sizes[i]++;
	
	/* Round up to full block, then add one for header */
	nu = ((nb + ABLKSIZE - 1) / ABLKSIZE) + 1;
	if((q = Allocp) == NULLHDR){
		Base.s.ptr = Allocp = q = &Base;
		Base.s.size = 1;
	}
	for(p = q->s.ptr; ; q = p, p = p->s.ptr){
		if(p->s.size >= nu){
			/* This chunk is at least as large as we need */
			if(p->s.size <= nu + 1){
				/* This is either a perfect fit (size == nu)
				 * or the free chunk is just one unit larger.
				 * In either case, alloc the whole thing,
				 * because there's no point in keeping a free
				 * block only large enough to hold the header.
				 */
				q->s.ptr = p->s.ptr;
			} else {
				/* Carve out piece from end of entry */
				p->s.size -= nu;
				p += p->s.size;
				p->s.size = nu;
			}
#ifdef	circular
			Allocp = q;
#endif
			p->s.ptr = p;	/* for auditing */
			Allocs++;
			Availmem -= p->s.size;
			p++;
			break;
		}
		if(p == Allocp && ((p = morecore(nu)) == NULLHDR)){
			Memfail++;
			break;
		}
	}
#ifdef	LARGEDATA
	/* On the brain-damaged Intel CPUs in "large data" model,
	 * make sure the pointer's offset field isn't null
	 * (unless the entire pointer is null).
	 * The Turbo C compiler and certain
	 * library functions like strrchr() assume this.
	 */
	if(FP_OFF(p) == 0 && FP_SEG(p) != 0){
		/* Return denormalized but equivalent pointer */
		return (void *)MK_FP(FP_SEG(p)-1,16);
	}
#endif
	return (void *)p;
}
/* Get more memory from the system and put it on the heap */
static HEADER HUGE *
morecore(nu)
unsigned nu;
{
	register char HUGE *cp;
	register HEADER HUGE *up;

	Morecores++;
	if ((int)(cp = (char HUGE *)sbrk(nu * ABLKSIZE)) == -1)
		return NULLHDR;
	up = (HEADER *)cp;
	up->s.size = nu;
	up->s.ptr = up;	/* satisfy audit */
	free((void *)(up + 1));
	Heapsize += nu*ABLKSIZE;
	Frees--;	/* Nullify increment inside free() */
	return Allocp;
}

/* Put memory block back on heap */
void
free(blk)
void *blk;
{
	register HEADER HUGE *p, HUGE *q;
	unsigned short HUGE *ptr;

	if(!istate())
		Intfree++;
	if(blk == NULL)
		return;		/* Required by ANSI */
	p = (HEADER HUGE *)blk - 1;
	/* Audit check */
	if(p->s.ptr != p){
		ptr = (unsigned short *)&blk;
		printf("free: WARNING! invalid pointer (0x%lx) proc %s\n",
		 ptol(blk),Curproc->name);
		stktrace();
		Invalid++;
		log(-1,"free: WARNING! invalid pointer (0x%lx) pc = 0x%x %x proc %s\n",
		 ptol(blk),ptr[-1],ptr[-2],Curproc->name);
		return;
	}
	Availmem += p->s.size;
	/* Search the free list looking for the right place to insert */
	for(q = Allocp; !(p > q && p < q->s.ptr); q = q->s.ptr){
		/* Highest address on circular list? */
		if(q >= q->s.ptr && (p > q || p < q->s.ptr))
			break;
	}
	if(p + p->s.size == q->s.ptr){
		/* Combine with front of this entry */
		p->s.size += q->s.ptr->s.size;
		p->s.ptr = q->s.ptr->s.ptr;
	} else {
		/* Link to front of this entry */
		p->s.ptr = q->s.ptr;
	}
	if(q + q->s.size == p){
		/* Combine with end of this entry */
		q->s.size += p->s.size;
		q->s.ptr = p->s.ptr;
	} else {
		/* Link to end of this entry */
		q->s.ptr = p;
	}
#ifdef	circular
	Allocp = q;
#endif
	Frees++;
	if(Memwait != 0)
		psignal(&Memwait,0);
}

#ifdef	notdef	/* Not presently used */
/* Move existing block to new area */
void *
realloc(area,size)
void *area;
unsigned size;
{
	unsigned osize;
	HEADER HUGE *hp;
	char HUGE *cp;

	hp = ((HEADER *)area) - 1;
	osize = (hp->s.size -1) * ABLKSIZE;

	free(area);
	if((cp = malloc(size)) != NULL && cp != area)
		memcpy((char *)cp,(char *)area,size>osize? osize : size);
	return cp;
}
#endif
/* Allocate block of cleared memory */
void *
calloc(nelem,size)
unsigned nelem;	/* Number of elements */
unsigned size;	/* Size of each element */
{
	register unsigned i;
	register char *cp;

	i = nelem * size;
	if((cp = malloc(i)) != NULL)
		memset(cp,0,i);
	return cp;
}
/* Version of malloc() that waits if necessary for memory to become available */
void *
mallocw(nb)
unsigned nb;
{
	register void *p;

	while((p = malloc(nb)) == NULL){
		Memwait++;
		pwait(&Memwait);
		Memwait--;
	}
	return p;
}
/* Version of calloc that waits if necessary for memory to become available */
void *
callocw(nelem,size)
unsigned nelem;	/* Number of elements */
unsigned size;	/* Size of each element */
{
	register unsigned i;
	register char *cp;

	i = nelem * size;
	cp = mallocw(i);
	memset(cp,0,i);
	return cp;
}
/* Return available memory on our heap plus available system memory */
unsigned long
availmem()
{
	return Availmem * ABLKSIZE + coreleft();
}

/* Print heap stats */
static int
dostat(argc,argv,envp)
int argc;
char *argv[];
void *envp;
{
	tprintf("heap size %lu avail %lu (%lu%%) morecores %lu coreleft %lu\n",
	 Heapsize,Availmem * ABLKSIZE,100L*Availmem*ABLKSIZE/Heapsize,
	 Morecores,coreleft());
	tprintf("allocs %lu frees %lu (diff %lu) alloc fails %lu invalid frees %lu\n",
		Allocs,Frees,Allocs-Frees,Memfail,Invalid);
	tprintf("interrupts-off calls to malloc %lu free %lu\n",Intalloc,Intfree);
	tprintf("garbage collections yellow %lu red %lu\n",Yellows,Reds);
	iqstat();
	return 0;
}

/* Print heap free list */
static int
dofreelist(argc,argv,envp)
int argc;
char *argv[];
void *envp;
{
	HEADER HUGE *p;
	int i = 0;

	for(p = Base.s.ptr;p != &Base;p = p->s.ptr){
		tprintf("%5lx %6lu",ptol((void *)p),p->s.size * ABLKSIZE);
		if(++i == 4){
			i = 0;
			if(tprintf("\n") == EOF)
				return 0;
		} else
			tprintf(" | ");
	}
	if(i != 0)
		tprintf("\n");
	return 0;
}
static int
dosizes(argc,argv,p)
int argc;
char *argv[];
void *p;
{
	int i;

	for(i=0;i<16;i += 4){
		tprintf("N>=%5u:%7ld| N>=%5u:%7ld| N>=%5u:%7ld| N>=%5u:%7ld\n",
		 1<<i,Sizes[i],	2<<i,Sizes[i+1],
		 4<<i,Sizes[i+2],8<<i,Sizes[i+3]);
	}
	return 0;
}
int
domem(argc,argv,p)
int argc;
char *argv[];
void *p;
{
	return subcmd(Memcmds,argc,argv,p);
}

static int
donibufs(argc,argv,p)
int argc;
char *argv[];
void *p;
{
	return setint(&Nibufs,"Interrupt pool buffers",argc,argv);
}
static int
doibufsize(argc,argv,p)
int argc;
char *argv[];
void *p;
{
	return setuns(&Ibufsize,"Interrupt buffer size",argc,argv);
}

static int
dothresh(argc,argv,p)
int argc;
char *argv[];
void *p;
{
	return setlong(&Memthresh,"Free memory threshold (bytes)",argc,argv);
}

/* Background memory compactor, used when memory runs low */
void
gcollect(i,v1,v2)
int i;	/* Args not used */
void *v1;
void *v2;
{
	void (**fp)();
	int red;

	for(;;){
		pause(1000L);	/* Run every second */
		/* If memory is low, collect some garbage. If memory is VERY
		 * low, invoke the garbage collection routines in "red" mode.
		 */
		if(availmem() < Memthresh){
			if(availmem() < Memthresh/2){
				red = 1;
				Reds++;
			} else {
				red = 0;
				Yellows++;
			}
			for(fp = Gcollect;*fp != NULL;fp++)
				(**fp)(red);
		}
	}
}