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/* cgc.c -*- Mode: C; comment-column: 40; -*-
 * $Header: /Volumes/share2/src/cmucl/cvs2git/cvsroot/src/lisp/cgc.c,v 1.1 1997/01/21 00:28:13 ram Exp $
 *
 * Conservative Garbage Collector for CMUCL x86.
 *
 * Copyright (c) Paul F Werkowski, 1996.
 *
 * There is absolutely NO WARRANTY associated with this code! Use
 * at your own risk! If you can't handle the fact that this may 
 * not work the way you want then just DELETE THIS FILE NOW!
 *
 * This code is based on software written by William Lott, and
 * Public Domain codes from Carnegie Mellon University.
 *
 * Received from William 27 Jul 95.
 *
 * Debug, FreeBSD hooks, and integration by Paul Werkowski
 *
 */
#include <stdio.h>
#include <assert.h>
#include <signal.h>
#include "os.h"				/* for SetSymbolValue */
#include "x86-validate.h"		/* for memory layout  */
#include "x86-lispregs.h"
#include "lisp.h"			/* for object defs */
#include "interrupt.h"			/* interrupt_handlers */
#include "internals.h"
#include "cgc.h"

#if !defined MIN
#define MIN(a,b)(((a)<(b))?(a):(b))
#define MAX(a,b)(((a)>(b))?(a):(b))
#endif

#include <unistd.h>
#include <stdlib.h>
#if defined unix
#include <sys/param.h>
#endif
#include <sys/types.h>
#include <sys/time.h>
#include <sys/resource.h>


#define dprintf(t,exp) if(t){printf exp ; fflush(stdout);}

/* Object representation details. The allocator/collector knows
 * almost nothing about lisp internals and is fairly general.
*/

#define ALIGN_BITS 3
#define ALIGN_BYTES (1<<ALIGN_BITS)
#define ALIGNEDP(addr) ((((int)addr)&(ALIGN_BYTES-1)) == 0)

/* Type of an object. */
typedef struct object
{
  long header;
  struct object*data[1];
} *obj_t;

/* Just leave unused space */
#define NOTE_EMPTY(ptr,bytes) {}


/* Collector datastructures */

#define BLOCK_BITS 16
#define BLOCK_BYTES (1<<BLOCK_BITS)
#define BLOCK_NUMBER(ptr) (((long)(ptr))>>BLOCK_BITS)
#define BLOCK_ADDRESS(num) ((void *)((num)<<BLOCK_BITS))

#define CHUNK_BITS 9
#define CHUNK_BYTES (1<<CHUNK_BITS)
#define CHUNK_NUMBER(ptr) (((long)(ptr))>>CHUNK_BITS)
#define CHUNK_ADDRESS(num) ((void *)((num)<<CHUNK_BITS))

#define BLOCK_CHUNKS (1<<(BLOCK_BITS-CHUNK_BITS))


#define ROUNDDOWN(val,x) ((val)&~((x)-1))
#define ROUNDUP(val,x) ROUNDDOWN((val)+(x)-1,x)

#define gc_abort() lose("GC invariant lost!  File \"%s\", line %d\n", \
			__FILE__, __LINE__)

#if 0
#define gc_assert(ex) {if (!(ex)) gc_abort();}
#else
#define gc_assert(ex)
#endif

char*alloc(int);


struct cluster {
    /* Link to the next cluster. */
    struct cluster *next;

    /* The number of blocks in this cluster. */
    int num_blocks;

    /* Pointer to the first region. */
    struct region *first_region;

    /* Table index by the chunk number of some pointer minus the chunk */
    /* number for the first region giving the number of chunks past */
    /* the chunk holding the region header that spans that pointer. */
    /* Actually, it might not be enough.  So after backing up that far, */
    /* try again. */
    unsigned char region_offset[1];
};

/* The first word of this is arranged to look like a fixnum
 * so as not to confuse 'room'.
 */
struct region {
  unsigned
  res1 :2, num_chunks :16, contains_small_objects :1, clean :1, hole :7;
  struct region **prev;
  struct region *next;
  struct space *space;
};

#define REGION_OVERHEAD ROUNDUP(sizeof(struct region), ALIGN_BYTES)


struct space {
    struct region *regions;
    struct region **regions_tail;
    char *alloc_ptr;
    char *alloc_end;
};

/* Chain of all the clusters. */
struct cluster *clusters = NULL;
static int num_clusters = 0;		/* for debugging */
int cgc_debug = 0;			/* maybe set from Lisp */
/* Table indexed by block number giving the cluster that block is part of. */
static struct cluster **block_table = NULL;

/* The allocated memory block_table is offset from. */
static struct cluster **block_table_base = NULL;

/* The maximum bounds on the heap. */
static void *heap_base = NULL;
static void *heap_end = NULL;

/* The two dynamic spaces. */
static struct space space_0 = { NULL };
static struct space space_1 = { NULL };
/* Pointers it whichever dynamic space is currently newspace and oldspace */
static struct space *newspace = NULL;
static struct space *oldspace = NULL;
/* Free lists of regions. */
static struct region *small_region_free_list = NULL;
static struct region *large_region_free_list = NULL;
static void move_to_newspace(struct region *region);

#if defined TESTING
static void print_region(struct region*r)
{
  dprintf(1,("[region %x %d <%x %x> %x]\n",
		     r,r->num_chunks,r->prev,r->next,r->space));
}
static void print_regions(struct region*r, char*str)
{
  printf("Regions %s:\n",str);
  for(; r != NULL; r = r->next)
    print_region(r);
}

static void print_space(struct space*s)
{
  struct region*r = s->regions;
  dprintf(1,("[space %x %s %s <%x - %x>]\n",
	     s,
	     (s == &space_0)? "S0" : "S1",
	     (s == newspace)? "NewSpace" : "OldSpace",
	     s->alloc_ptr, s->alloc_end));
  print_regions(r,"");

}
void print_spaces()
{
  print_space(&space_0);
  print_space(&space_1);
  print_regions(large_region_free_list,"LRFL");
  print_regions(small_region_free_list,"SRFL");
}
void print_cluster(struct cluster*cluster)
{
  printf("[cluster %x >%x %d]\n",cluster,cluster->next,cluster->num_blocks);
  print_regions(cluster->first_region,"cluster");
}
void print_clusters()
{
  struct cluster*cluster;
  for(cluster=clusters; cluster != NULL; cluster = cluster->next)
    print_cluster(cluster);
}
#endif /* TESTING */
  

/* Allocation/deallocation routines */

static void init_region(struct region *region, int nchunks)
{
    int region_block = BLOCK_NUMBER(region);
    struct cluster *cluster = block_table[region_block];
    int offset = CHUNK_NUMBER(region) - CHUNK_NUMBER(cluster->first_region);
    int i;
    dprintf(0,("init region %x %d\n",region,nchunks));
    *(long*)region = 0;			/* clear fields */
    region->num_chunks = nchunks;
    if (nchunks > UCHAR_MAX) {
	for (i = 0; i < UCHAR_MAX; i++)
	    cluster->region_offset[offset + i] = i;
	for (; i < nchunks; i++)
	    cluster->region_offset[offset + i] = UCHAR_MAX;
    }
    else {
	for (i = 0; i < nchunks; i++)
	    cluster->region_offset[offset + i] = i;
    }
}

static struct region *maybe_alloc_large_region(int nchunks)
{
    struct region *region, **prev;

    prev = &large_region_free_list;
    while ((region = *prev) != NULL) {
	if (region->num_chunks >= nchunks) {
	    if (region->num_chunks == nchunks)
		*prev = region->next;
	    else {
		struct region *new
		    = (struct region *)((char *)region + nchunks*CHUNK_BYTES);
		init_region(new, region->num_chunks - nchunks);
		new->next = region->next;
		new->prev = NULL;
		new->space = NULL;
		*prev = new;
		region->num_chunks = nchunks;
	    }
	    region->next = NULL;
	    region->prev = NULL;
	    region->space = NULL;
	    return region;
	}
	prev = &region->next;
    }
    return NULL;
}


/* from os_zero */
static void cgc_zero(addr, length)
os_vm_address_t addr;
os_vm_size_t length;
{
  os_vm_address_t block_start = os_round_up_to_page(addr);
  os_vm_address_t end = addr + length;
  os_vm_size_t block_size;
  
  
  if(block_start > addr)
    bzero((char *)addr, MIN(block_start - addr, length));

  if(block_start < end)
    {
      length -= block_start - addr;
      
      block_size =os_trunc_size_to_page(length);
      
      if(block_size < length)
	bzero((char *)block_start + block_size,length - block_size);
  
      if (block_size != 0)
	{
	  /* Now deallocate and allocate the block so that it */
	  /* faults in  zero-filled. */
	  
	  os_invalidate(block_start,block_size);
	  addr=os_validate(block_start,block_size);
	  
	  if(addr == NULL || addr != block_start)
	    fprintf(stderr,"cgc_zero: block moved, 0x%08x ==> 0x%08x!\n",
		    block_start,addr);
	}
    }
}

static void compact_cluster(struct cluster *cluster)
{
  int show = 0;
  struct region *region = cluster->first_region;
  struct region *end =
    (struct region *)((char *)region + cluster->num_blocks * BLOCK_BYTES);
  int grown = 0;
  struct region *large_additions = NULL;
  struct region **large_prev = &large_additions;
  struct region *small_additions = NULL;
  struct region **small_prev = &small_additions;
  
  dprintf(show,("compact cluster %x\n",cluster));
  while (region < end) {
    struct region *next =
      (struct region *) ((char *)region + region->num_chunks*CHUNK_BYTES);
    if (region->space != newspace) {	/* was == NULL */
      if (next < end && next->space != newspace) { /* was == NULL */
	gc_assert(region->space == NULL);
	gc_assert(next->space == NULL);
	gc_assert(region->num_chunks > 0);
	gc_assert(next->num_chunks > 0);
	region->num_chunks += next->num_chunks;
	grown = 1;
      }
      else {
	if (grown) {
	  init_region(region, region->num_chunks);
	  region->space = NULL;
	  grown = 0;
	}
	{
	  int ovh = REGION_OVERHEAD;
	  cgc_zero((os_vm_address_t)((char*)region + ovh),
		  (os_vm_size_t)(region->num_chunks*CHUNK_BYTES) - ovh);
	}

	if(region->num_chunks == 1) {
	  *small_prev = region;
	  small_prev = &region->next;
	}
	else {
	  *large_prev = region;
	  large_prev = &region->next;
	}
	region = next;
      }
    }
    else
      region = next;
  }
  
  *large_prev = large_region_free_list;
  large_region_free_list = large_additions;
  *small_prev = small_region_free_list;
  small_region_free_list = small_additions;
}

static void compact_free_regions()
{
  struct cluster*cluster;
    large_region_free_list = NULL;
    small_region_free_list = NULL;

    for (cluster = clusters; cluster != NULL; cluster = cluster->next)
	compact_cluster(cluster);
}

/* WL code arranged to allocate new space via the sbrk() mechanism.
 * However, I am going to start by allocating from the standard dynamic
 * space. The idea is to use the normal allocation scheme for initial
 * system build and switch to the cgc allocator when starting up a
 * saved image when dynamic space is hopefully clean.
 */
static struct region*new_region(int nblocks)
{
  /* take from existing dynamic space */
  char*new = (char*)SymbolValue(ALLOCATION_POINTER);
  struct region*region = (struct region*)(ROUNDUP((long)new,BLOCK_BYTES));
  int bn = BLOCK_NUMBER(region);
  new += (nblocks * BLOCK_BYTES + ((char*)region - new));
  SetSymbolValue(ALLOCATION_POINTER,(lispobj)new);
    return region;
}

static void new_cluster(int min_blocks)
{
    int nblocks = min_blocks < 4 ? 4 : min_blocks;
    int nchunks = nblocks << (BLOCK_BITS-CHUNK_BITS);
    int i;
    struct cluster *cluster = malloc(sizeof(struct cluster) + nchunks-1);
    struct region*region = new_region(nblocks);

    int bn = BLOCK_NUMBER(region);
    dprintf(cgc_debug,("new cluster %x region@%x\n",cluster,region));
    for (i = 0; i < nblocks; i++)
      block_table[bn+i] = cluster;

    num_clusters++;
    cluster->next = clusters;
    clusters = cluster;
    cluster->num_blocks = nblocks;
    cluster->first_region = region;

    init_region(region, nchunks);

    region->next = large_region_free_list;
    large_region_free_list = region;
    region->prev = NULL;
    region->space = NULL;
}

unsigned long cgc_bytes_allocated = 0;	/* Seen by (dynamic-usage) */
static unsigned long auto_gc_trigger = 0;
static int maybe_gc_called = 0;

static struct region *alloc_large_region(int nchunks)
{
  struct region *region;
  {
    region = maybe_alloc_large_region(nchunks);

    if (region == NULL)
      {
	new_cluster((nchunks + BLOCK_CHUNKS - 1) >> (BLOCK_BITS-CHUNK_BITS));
	region = maybe_alloc_large_region(nchunks);
	gc_assert(region != NULL);
      }
  }
  gc_assert(region->space == NULL);
  return region;
}

static struct region *alloc_small_region()
{
    struct region *region = small_region_free_list;

    if (region == NULL)
	region = alloc_large_region(1);
    else
	small_region_free_list = region->next;
    region->next = NULL;
    region->prev = NULL;
    region->space = NULL;
    move_to_newspace(region);
    return region;
}

static int chunks_freed = 0;

static void free_region(struct region *region)
{
  gc_assert(region->space && region->space == oldspace);
  gc_assert(region->num_chunks > 0);

  region->space = NULL;			/* for compact_cluster? */
  region->prev = NULL;			/* housekeeping I hope */
  chunks_freed += region->num_chunks;

  if (region->num_chunks == 1)
    {
      region->next = small_region_free_list;
      small_region_free_list = region;
    }
  else
    {
      region->next = large_region_free_list;
      large_region_free_list = region;
    }
}

static void *alloc_large(int nbytes)
{
    int nchunks = (nbytes+REGION_OVERHEAD+CHUNK_BYTES-1) >> CHUNK_BITS;
    struct region *region = alloc_large_region(nchunks);
    region->contains_small_objects = 0;
    region->next = NULL;
    region->prev = NULL;
    region->space = NULL;
    cgc_bytes_allocated += region->num_chunks*CHUNK_BYTES;
    move_to_newspace(region);
    return (char *)region + REGION_OVERHEAD;
}

void *cgc_alloc(int nbytes)
{
  void*res;
  dprintf(0,("alloc %d\n", nbytes));

  if (nbytes > (CHUNK_BYTES - REGION_OVERHEAD))
    res = alloc_large(nbytes);
  else
    {
      struct space *space = newspace;
      if ((space->alloc_ptr + nbytes) > space->alloc_end)
	{
	  struct region *region;
	  if(space->alloc_ptr != NULL)
	    {
	      int hole = space->alloc_end - space->alloc_ptr;
	      if(hole >= ALIGN_BYTES)
		/* This wastes the space, eg suppose one cons
		 * has been allocated then a request for
		 * a maximum sized small obj comes in. I'd like
		 * to remember that there is still a lot of
		 * room left in this region. Maybe I could actually
		 * use the small_region_free_list in some way.
		 */
		NOTE_EMPTY(space->alloc_ptr, hole);
	    }
	  region = alloc_small_region();
	  region->contains_small_objects = 1;
	  space->alloc_ptr = (char *)region + REGION_OVERHEAD;
	  space->alloc_end = (char *)region + CHUNK_BYTES;
	  cgc_bytes_allocated += region->num_chunks*CHUNK_BYTES;
	}
      
      res = space->alloc_ptr;
      space->alloc_ptr += ROUNDUP(nbytes, ALIGN_BYTES);
    }
  return res;
}


static void move_to_newspace(struct region *region)
{
  /* (maybe) unlink region from oldspace and add to tail of 
   * newspace regions. Don't attempt to move a region that
   * is already in newspace.
   */
    struct space *space = newspace;
    if(region->space == oldspace)
      {
	/* Remove region from list. The prev slot holds
	 * the address of the 'next' slot of the previous
	 * list entry, not a pointer to that region (why?)
	 */
	*region->prev = region->next;
	if(region->next)
	  region->next->prev = region->prev;
	if(region->space->regions_tail == &region->next)
	  region->space->regions_tail = region->prev;
      }
    /* Append to newspace unless it has already been promoted. */
    if(region->space != newspace)
      {
	region->prev = space->regions_tail;
	region->next = NULL;
	*space->regions_tail = region;
	space->regions_tail = &region->next;
	region->space = space;
      }
}

static struct region *find_region(void *ptr)
{
    struct cluster *cluster;
    int cluster_chunk_num;
    int chunk_num;
    unsigned char delta;

    ptr = (void*)((int) ptr & ~0x3);
    if (ptr < heap_base || ptr >= heap_end)
	return NULL;

    cluster = block_table[BLOCK_NUMBER(ptr)];
    if (cluster == NULL)
	return NULL;

    if (ptr < (void*)cluster->first_region)
	return NULL;

    cluster_chunk_num = CHUNK_NUMBER(cluster->first_region);
    chunk_num = CHUNK_NUMBER(ptr);

    while (delta = cluster->region_offset[chunk_num - cluster_chunk_num])
	chunk_num -= delta;

    return CHUNK_ADDRESS(chunk_num);
}

/* Interface to std collector */
static inline boolean
from_space_p(lispobj obj)
{
  struct region*region=find_region((void*)obj);
  return (region != NULL && region->space == oldspace);
}
static inline boolean
new_space_p(lispobj obj)
{
  struct region*region=find_region((void*)obj);
  return (region != NULL && region->space == newspace);
}
static inline boolean
static_space_p(lispobj obj)
{
  return (STATIC_SPACE_START < obj
	  && obj < SymbolValue(STATIC_SPACE_FREE_POINTER));
}

/* Predicate that returns true if an object is a pointer. */
#undef  POINTERP
#define POINTERP(obj) Pointerp((obj)->header)

/* Predicate that returns true if an object has been forwarded. */
#define FORWARDED(obj) ((obj_t)(obj)->header == (obj_t)0x1)

/* Returns the forwarding pointer for the given object. */
#define FORWARDING_PTR(obj) ((lispobj)(obj)->data[0])

/* Marks obj as forwarded to new */
#define DEPOSIT_FORWARDING_PTR(obj,new) \
 ((obj_t)(obj)->header = 0x1, (obj_t)(obj)->data[0] = (obj_t)new)

/* Returns an obj_t for the object starting at addr */
#define OBJECT_AT(addr) ((obj_t)(addr))

/* Returns the size (in bytes) of obj. */
#define OBJECT_SIZE(obj) (sizeOfObject((obj_t)obj)<<2)

/* Scavenges an object. */
#define SCAVENGE_OBJECT(obj) scavengex((lispobj*)obj)

#if 0
/* Makes a region of memory look like some kind of object. */
#define NOTE_EMPTY(ptr,bytes) \
    (((obj_t)ptr)->header = (((bytes+ALIGN_BYTES-1)>>ALIGN_BITS)<<8) | 1)
#endif

static unsigned long bytes_copied = 0;
#   define  HAVE_FASTCOPY
#if defined HAVE_FASTCOPY
#define COPYDUAL(a,b,c) fastcopy16(a,b,c)
void fastcopy16(void*,void*,size_t);
#else
#define COPYDUAL(a,b,c) memmove(a,b,c)
#endif
static inline lispobj
copy(lispobj taggedobj)
{
  obj_t source = (obj_t)PTR(taggedobj);
  int nbytes = OBJECT_SIZE(source);
  gc_assert(Pointerp(taggedobj));
  gc_assert(!(nbytes & (ALIGN_BYTES-1)));
  {
    int lowtag = LowtagOf(taggedobj);
    obj_t newobj = cgc_alloc(nbytes);
    COPYDUAL(newobj, source, nbytes);
    bytes_copied += nbytes;
    return ((lispobj)newobj | lowtag);
  }
}


#define CEILING(x,y) (((x) + ((y) - 1)) & (~((y) - 1)))
#define NWORDS(x,y) (CEILING((x),(y)) / (y))

#define WEAK_POINTER_NWORDS \
	CEILING((sizeof(struct weak_pointer) / sizeof(lispobj)), 2)
static struct weak_pointer *weak_pointers;


/* Scavenging:
 * CMU CL objects can be classified as BOXED, UNBOXED or other.
 * Boxed objects have a header containing length and type followed
 * by LENGTH tagged object descriptors which may be pointers.
 * UNBOXED objects have a header but the data is other than
 * tagged descriptors, such as floats, bignums, saps or code.
 * Others (code) contain a mix of boxed and unboxed and some
 * (cons) are like BOXED but without header. The scavenger needs
 * to consider these different kinds of objects. I will use a
 * table indexed by type to detect the simple cases of boxed
 * or unboxed.
 */
#define IMMED_OR_LOSE(thing) gc_assert(sct[TypeOf(thing)].sc_kind == SC_IMMED)
static void scavenge_pointer(lispobj*);
static int noise = 0;

typedef struct { unsigned sc_kind : 3, ve_l2bits : 5;} OSC_t;

OSC_t make_OSC(int kind, int log2bits)
{
  OSC_t thing;
  thing.sc_kind = kind;
  thing.ve_l2bits = log2bits;
  return thing;
}
#define SETSCT(indx,kind,logbits) sct[indx] = make_OSC(kind,logbits)
#define SC_ISBOXED 1
#define SC_UNBOXED 2
#define SC_IMMED   3
#define SC_POINTER 4
#define SC_VECTOR  5
#define SC_STRING  6
#define SC_OTHER   7
#define SC_LOSER   0
static OSC_t sct[256];

int sizeOfObject(obj_t obj)
{
  int obj_type = TypeOf(obj->header);
  OSC_t class = sct[obj_type];
  struct vector*vector;
  int length = 1;
  int nwords = 1;
  switch (class.sc_kind)
    {
    case SC_POINTER:
    case SC_IMMED:
      return 1;
    case SC_ISBOXED:
    case SC_UNBOXED:
      gc_assert(HeaderValue(obj->header) > 0);
      nwords = length = HeaderValue(obj->header) + 1;
      break;
    case SC_STRING:
    case SC_VECTOR:
      {
	int log2bits = class.ve_l2bits;
	int bits_per_el = 1 << log2bits;
	int extra = 0;
	int els_per_word = 1 << (5 - log2bits);
	if(log2bits > 5)
	  {
	    els_per_word = 1;
	    extra = log2bits - 5;
	  }
	length = ((struct vector*)obj)->length;
	length = fixnum_value(length);	/* Zero Length IS valid */
	length +=  (class.sc_kind == SC_STRING);
	length <<= extra;
	nwords = NWORDS(length, els_per_word);
	nwords += 2;			/* header + length */
      }
      break;
    case SC_OTHER:
      switch(obj_type)
	{
	case type_CodeHeader:
	  {
	    struct code *code;
	    int nheader_words, ncode_words;
	    code = (struct code *)obj;
	    ncode_words = fixnum_value(code->code_size);
	    nheader_words = HeaderValue(code->header);
	    nwords = ncode_words + nheader_words;
	  } break;
	default:
	  fprintf(stderr,"GC losage: no size for other type %d\n",obj_type);
	  gc_abort();
	}
      break;
    default:
      fprintf(stderr,"GC losage: no size for other type %d\n",obj_type);
      gc_abort();
    }
  return CEILING(nwords,2);
}

static void init_osc()
{
  int i;
  for (i = 0; i < 256; i++)
    SETSCT(i ,SC_LOSER, 0);
  for (i = 0; i < 32; i++)
    {
      SETSCT(type_EvenFixnum|(i<<3)	,SC_IMMED,0);
      SETSCT(type_FunctionPointer|(i<<3),SC_POINTER,0);
      /* OtherImmediate0 */
      SETSCT(type_ListPointer|(i<<3)	,SC_POINTER,0);
      SETSCT(type_OddFixnum|(i<<3) 	,SC_IMMED,0);
      SETSCT(type_InstancePointer|(i<<3),SC_POINTER,0);
      /* OtherImmediate1 */
      SETSCT(type_OtherPointer|(i<<3) 	,SC_POINTER,0);
    }
  SETSCT(type_Bignum			,SC_UNBOXED,0);
  SETSCT(type_Ratio			,SC_ISBOXED,0);
  SETSCT(type_SingleFloat		,SC_UNBOXED,0);
  SETSCT(type_DoubleFloat		,SC_UNBOXED,0);
  SETSCT(type_Complex			,SC_ISBOXED,0);
  SETSCT(type_SimpleArray		,SC_ISBOXED,0);
  SETSCT(type_SimpleString		,SC_STRING,3);
  SETSCT(type_SimpleBitVector		,SC_VECTOR,0);
  SETSCT(type_SimpleVector		,SC_VECTOR,5);
  SETSCT(type_SimpleArrayUnsignedByte2	,SC_VECTOR,1);
  SETSCT(type_SimpleArrayUnsignedByte4	,SC_VECTOR,2);
  SETSCT(type_SimpleArrayUnsignedByte8	,SC_VECTOR,3);
  SETSCT(type_SimpleArrayUnsignedByte16	,SC_VECTOR,4);
  SETSCT(type_SimpleArrayUnsignedByte32	,SC_VECTOR,5);
  SETSCT(type_SimpleArraySingleFloat	,SC_VECTOR,5);
  SETSCT(type_SimpleArrayDoubleFloat	,SC_VECTOR,6);
  SETSCT(type_ComplexString		,SC_ISBOXED,0);
  SETSCT(type_ComplexBitVector		,SC_ISBOXED,0);
  SETSCT(type_ComplexVector		,SC_ISBOXED,0);
  SETSCT(type_ComplexArray		,SC_ISBOXED,0);
  SETSCT(type_CodeHeader		,SC_OTHER,0);
  SETSCT(type_FunctionHeader		,SC_OTHER,0);
  SETSCT(type_ClosureFunctionHeader	,SC_OTHER,0);
  SETSCT(type_ReturnPcHeader		,SC_OTHER,0);
  SETSCT(type_ClosureHeader		,SC_ISBOXED,0);
  SETSCT(type_FuncallableInstanceHeader	,SC_ISBOXED,0);
  SETSCT(type_ByteCodeFunction		,SC_ISBOXED,0);
  SETSCT(type_ByteCodeClosure		,SC_ISBOXED,0);
  SETSCT(type_DylanFunctionHeader	,SC_ISBOXED,0);

  SETSCT(type_ValueCellHeader		,SC_ISBOXED,0);
  SETSCT(type_SymbolHeader		,SC_ISBOXED,0);
  SETSCT(type_BaseChar			,SC_IMMED,0);
  SETSCT(type_Sap			,SC_UNBOXED,0);
  SETSCT(type_UnboundMarker		,SC_IMMED,0);
  SETSCT(type_WeakPointer		,SC_UNBOXED,0);
  SETSCT(type_InstanceHeader		,SC_ISBOXED,0);
  SETSCT(type_Fdefn			,SC_ISBOXED,0);
}

static lispobj* scavenge(lispobj*,int);
static lispobj*scavenge_object(lispobj*);
static lispobj*scavengex(lispobj*);

static inline scavenge_1word_obj(lispobj*addr)
{
  if(Pointerp(*addr))
    {
      if(*addr != NIL && *addr != T)
	scavenge_pointer(addr);
    }
  else
    IMMED_OR_LOSE(*addr);
}
static int debug_code = 0;
static int
scav_code_header(lispobj*where)
{
  lispobj object = *where;
  struct code *code;
  int i,nheader_words, ncode_words, nwords;
  lispobj fheaderl;
  struct function *fheaderp;
  dprintf(0,("code: %x %x\n",where,object));
  code = (struct code *) where;
  ncode_words = fixnum_value(code->code_size);
  nheader_words = HeaderValue(object);
  nwords = ncode_words + nheader_words;
  nwords = CEILING(nwords, 2);
  /* Scavenge the boxed section of the code data block */
  /* NOTE: seeing a problem where the trace_table_offset slot
   * is a bogus list pointer instead of a fixnum such that 
   * junk gets moved to newspace which causes problems later.
   * Purify doesn't look at that slot (a bug?). Need
   * to figure out how it happens. Ans: from loading top-level
   * forms that init byte-compiled functions like "defun fcn".
   * Fix the loader to not do this and save some space!
   */
  for(i=1; i < nheader_words; i++)
    scavenge_1word_obj(where + i);

  /* Scavenge the boxed section of each function object in the 
   * code data block.
   */
  fheaderl = code->entry_points;
  while (fheaderl != NIL) {
    fheaderp = (struct function *) PTR(fheaderl);
    gc_assert(TypeOf(fheaderp->header) == type_FunctionHeader);
    scavenge_1word_obj(&fheaderp->name);
    scavenge_1word_obj(&fheaderp->arglist);
    scavenge_1word_obj(&fheaderp->type);
    fheaderl = fheaderp->next;
  }
  return nwords;
}

#define RAW_ADDR_OFFSET (6*sizeof(lispobj) - type_FunctionPointer)
#ifdef i386
static void scavenge_fcn_header(struct function*object)
{
  struct function*fheader = object;
  unsigned long offset = HeaderValue(fheader->header) * 4;
  /* Ok, we don't transport code here, but we do need to
   * scavenge the constants and functions (of which this is one).
   * This should be done as part of scavenging a live code object
   * and we could now be trying to do CPR on a corpse!
   */
  struct code*code = (struct code *) ((unsigned long) fheader - offset);
  gc_assert(TypeOf(fheader->header) == type_FunctionHeader);
  scav_code_header((lispobj*)code);
}

static int docode=0;			/* maybe not needed */
static int
scav_closure_header(struct closure*closure)
{
  /* Could also be a funcallable_instance. The x86 port has the
   * raw code address in the function slot, not a lisp object.
   * However, the function object is a known distance from the code.
   */
  lispobj fun, fheader1;
  int i,words;
  gc_assert(ALIGNEDP(closure));
  words = HeaderValue(closure->header);
  fun = closure->function - RAW_ADDR_OFFSET;
  /* This needs to be done to get at live code. I now have no
   * way to know if this has already been scavenged so I assume
   * that it hasn't. Code that has been seen by purify is
   * supposed RO and doesn't (shouldn't) need to be looked at
   * so this maybe really redundant.
   *
   * I have seen one case where FI was incomplete with function
   * and lexenv slots == 0! Is this a bug?
   *
   * Update, it appears this is not needed. I will disable execution
   * by default but leave the code here in case something breaks.
   */
  if(docode && static_space_p(closure->function))
    scavenge_fcn_header((struct function*)PTR(fun));
  else					/* "normal" */
    scavenge_1word_obj(&fun);

  /* Now the boxed part of the closure header. */
  for(i = 0; i < words - 1; i++)
    scavenge_1word_obj(&closure->info[i]);

  return CEILING(words + 1, 2);
}
static int fnoise=0;			/* experimental */
static int
scav_fdefn(lispobj*where)
{
  /* I don't know if this is really needs to be special cased here.
   * raw_address  should look like a fixnum and function is in static
   * space -- unless it is pointing to something in C like closure_tramp
   * or maybe undefined_tramp.
   * Actually function is in dynamic space if it is a byte-function!
   * Hmm, have seen case of function slot containing 1. Bug?
   */
  struct fdefn * fdefn = (struct fdefn*)where;
  int words = HeaderValue(fdefn->header);
  int fix_func = ((char*)(fdefn->function+RAW_ADDR_OFFSET) == fdefn->raw_addr);
  scavenge_pointer(&fdefn->name);
  if(fnoise && LowtagOf(fdefn->function) == type_FunctionPointer)
    {
      obj_t fcnobj = (obj_t)PTR(fdefn->function);
      switch(TypeOf(fcnobj->header))
	{
	  /* Can only be in static space and may need to scavenge code object.
	   * Won't be noticed by scavenge_pointer().
	   */
	case type_FunctionHeader:
	  scavenge_fcn_header((struct function*)fcnobj);
	  break;
	  /* If in static space it was moved there by purify and we are
	   * doing normal scavenge. Handle normally.
	   */
	case type_FuncallableInstanceHeader:
	case type_ClosureHeader:
	  scavenge_pointer(&fdefn->function);
	  break;
	default:
	  dprintf(1,("Ignoring bogus value %x for fdefn function.\n", 
		     *fcnobj));
	}
    }
  else
    /* NIL for undefined function? */
    scavenge_pointer(&fdefn->function);

  if (fix_func)
    { /* This shouldn't be needed yet. */
      fdefn->raw_addr = (char *)(fdefn->function + RAW_ADDR_OFFSET);
    }
  return sizeof(struct fdefn) / sizeof(lispobj);
}

#endif

/* List scavenger taken from gc.c and adapted */

static FILE*log=NULL;
static int scav_ro = 0;			/* for testing  */
static int debug=0;
static void*trapaddr=0;
void check_trap(void*addr)
{
  fprintf(stderr,"Trapped @ %x\n",addr);
}

static lispobj
trans_list(lispobj object)
{
  lispobj new_list_pointer;
  struct cons *cons, *new_cons;
  int n=0;
  lispobj  cdr;

  cons = (struct cons *) PTR(object);
  
  /* copy 'object' */
  new_cons = (struct cons *) cgc_alloc(sizeof(struct cons));
  new_cons->car = cons->car;
  new_cons->cdr = cons->cdr; /* updated later */
  new_list_pointer = (lispobj)new_cons | LowtagOf(object);
  bytes_copied += sizeof(struct cons);
#if 0
  if(scav_ro>1)check_trap(object);
  if(log)fprintf(log,"( %d cons @ #x%x -> #x%x car #x%x)\n",