source: buchla-68k/orig/lib/INCLUDE/MALLOC.H@ eee74cd

Last change on this file since eee74cd was 3ae31e9, checked in by Thomas Lopatic <thomas@…>, 7 years ago

Imported original source code.

  • Property mode set to 100755
File size: 6.0 KB
Line 
1/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
2 * MALLOC.H -- header file for A "smarter" malloc
3 * Version 4 -- 1988-05-03 -- USENET
4 *
5 * A "smarter" malloc Original code by William L. Sebok
6 *
7 * Modified for Aztec C-II by D.N. Lynx Crowe
8 *
9 * 1986-12-30 Made long constants explicit as fix for bug in compiler
10 * 1987-01-01 Made long constants into variables to work around compiler bug
11 * 1988-05-03 Modified to work on the Atari under GEMDOS
12 * 1988-05-03 Added define of SMARTMAL so we know what we've got
13 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
14 * Algorithm:
15 * Assign to each area an index "n". This is currently proportional to
16 * the log 2 of size of the area rounded down to the nearest integer.
17 * Then all free areas of storage whose length have the same index n are
18 * organized into a chain with other free areas of index n (the "bucket"
19 * chain). A request for allocation of storage first searches the list of
20 * free memory. The search starts at the bucket chain of index equal to
21 * that of the storage request, continuing to higher index bucket chains
22 * if the first attempt fails.
23 * If the search fails then new memory is allocated. Only the amount of
24 * new memory needed is allocated. Any old free memory left after an
25 * allocation is returned to the free list.
26 *
27 * All memory areas (free or busy) handled by malloc are also chained
28 * sequentially by increasing address (the adjacency chain). When memory
29 * is freed it is merged with adjacent free areas, if any. If a free area
30 * of memory ends at the end of memory (i.e. at the break), and if the
31 * variable "endfree" is non-zero, then the break is contracted, freeing
32 * the memory back to the system.
33 *
34 * Notes:
35 * ov_len field includes sizeof(struct overhead)
36 * adjacency chain includes all memory, allocated plus free.
37 */
38
39/* **************************** Machine Dependencies ******************** */
40
41/* the following items may need to be configured for a particular machine */
42
43#define void int /* Aztec C doesn't have voids */
44
45/* alignment requirement for machine (in bytes) */
46
47#define NALIGN 2
48
49/* size of an integer large enough to hold a character pointer */
50
51typedef long Size;
52
53/*
54 * CURBRK returns the value of the current system break, i.e., the system's
55 * idea of the highest legal address in the data area. It is defined as
56 * a macro for the benefit of systems that have provided an easier way to
57 * obtain this number (such as in an external variable)
58 */
59
60#ifndef CURBRK
61
62#define CURBRK sbrk(0)
63extern char *sbrk();
64
65#else CURBRK
66
67#if CURBRK == curbrk
68extern Size curbrk;
69#endif
70
71#endif CURBRK
72
73/*
74 * note that it is assumed that CURBRK remembers the last requested break to
75 * the nearest byte (or at least the nearest word) rather than the nearest page
76 * boundary. If this is not true then the following BRK macro should be
77 * replaced with one that remembers the break to within word-size accuracy.
78 */
79
80#ifndef BRK
81
82#define BRK(x) brk(x)
83extern char *brk();
84
85#endif BRK
86
87/*
88 define NBUCKETS as 18 for big machines, 10 for small ones
89 and adjust the definitions of mlsizes[] and buckets[], below.
90*/
91
92#define NBUCKETS 18
93
94/* ***************** END of machine dependent portion ******************* */
95
96struct qelem {
97
98 struct qelem *q_forw;
99 struct qelem *q_back;
100};
101
102struct overhead {
103
104 struct qelem ov_adj; /* adjacency chain pointers */
105 struct qelem ov_buk; /* bucket chain pointers */
106 long ov_magic; /* MAGIC number */
107 Size ov_len; /* length of the area in bytes */
108};
109
110/*
111 * The following macros depend on the order of the elements in struct overhead
112 */
113
114#define TOADJ(p) ((struct qelem *)(p))
115#define FROMADJ(p) ((struct overhead *)(p))
116#define FROMBUK(p) ((struct overhead *)( (char *)p - sizeof(struct qelem)))
117#define TOBUK(p) ((struct qelem *)( (char *)p + sizeof(struct qelem)))
118
119#define XM_FREE 0x548A934CL /* MAGIC for free blocks */
120#define XM_BUSY 0xC139569AL /* MAGIC for busy blocks */
121
122#define M_FREE m_free
123#define M_BUSY m_busy
124
125#ifdef MALLOC
126
127/*
128 * return to the system memory freed adjacent to the break
129 * default is Off
130 */
131
132char endfree = 0; /* WARNING -- this isn't PROMable */
133
134/*
135 * M_FREE and M_BUSY used to be MAGIC_FREE and MAGIC_BUSY
136 * m_free and m_busy were added to work around a BUG in Aztec CII
137 */
138
139long m_free = XM_FREE;
140long m_busy = XM_BUSY;
141
142/* head of adjacency chain */
143
144struct qelem adjhead = { &adjhead, &adjhead };
145
146/* *************** More Machine Dependencies *********************** */
147
148/* sizes of buckets currently proportional to log 2() */
149/* must match NBUCKETS, above */
150
151Size mlsizes[] = {0, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384,
152
153 /* trim here if on a small machine */
154
155 32768, 65536, 131072, 262144, 524288, 1048576, 2097152, 4194304};
156
157/* head of bucket chains */
158/* must match NBUCKETS, above */
159
160struct qelem buckets[NBUCKETS] = {
161
162 &buckets[0], &buckets[0], &buckets[1], &buckets[1],
163 &buckets[2], &buckets[2], &buckets[3], &buckets[3],
164 &buckets[4], &buckets[4], &buckets[5], &buckets[5],
165 &buckets[6], &buckets[6], &buckets[7], &buckets[7],
166 &buckets[8], &buckets[8], &buckets[9], &buckets[9],
167
168 /* trim here if on a small machine */
169
170 &buckets[10], &buckets[10], &buckets[11], &buckets[11],
171 &buckets[12], &buckets[12], &buckets[13], &buckets[13],
172 &buckets[14], &buckets[14], &buckets[15], &buckets[15],
173 &buckets[16], &buckets[16], &buckets[17], &buckets[17]
174};
175
176/* ********************* End of Machine Dependencies ********************* */
177
178void (*mlabort)() = {0};
179
180#else
181
182extern char endfree;
183extern struct qelem adjhead, buckets[NBUCKETS];
184extern Size mlsizes[NBUCKETS];
185extern void (*mlabort)();
186extern long m_free, m_busy;
187
188#endif
189
190extern void insque(), remque();
191extern void free(), mllcerr();
192extern char *malloc(), *realloc();
193
194#ifdef debug
195
196# define ASSERT(p,q) if (!(p)) mllcerr(q)
197
198#else
199
200# define ASSERT(p,q)
201
202#endif
203
204#define SMARTMAL
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