|
99
|
1
|
|
|
2 typedef struct header
|
|
|
3 { struct header *ptr;
|
|
|
4 unsigned size;
|
|
|
5 } HEADER;
|
|
|
6
|
|
|
7 HEADER base,*allocp,*heap;
|
|
|
8
|
|
|
9 char *malloc(s)
|
|
|
10 unsigned s;
|
|
|
11 {HEADER *p,*q;
|
|
|
12 int nunits;
|
|
|
13 nunits = 1 + (s + sizeof(HEADER) - 1) / sizeof(HEADER);
|
|
|
14 if ((q = allocp) == NULL)
|
|
|
15 { base.ptr = allocp = q = &base;
|
|
|
16 base.size = 0;
|
|
|
17 }
|
|
|
18 for (p = q->ptr; ; q = p,p = p->ptr)
|
|
|
19 { if (p->size >= nunits)
|
|
|
20 { if (p->size == nunits)
|
|
|
21 q->ptr = p->ptr;
|
|
|
22 else
|
|
|
23 { p->size -= nunits;
|
|
|
24 p += p->size;
|
|
|
25 p->size = nunits;
|
|
|
26 }
|
|
|
27 allocp = q;
|
|
|
28 clearblock(p);
|
|
|
29 return ((char *)(p + 1));
|
|
|
30 }
|
|
|
31 if (p == allocp)
|
|
|
32 if ((p = morecore(nunits)) == NULL)
|
|
|
33 return(NULL);
|
|
|
34 }
|
|
|
35 }
|
|
|
36
|
|
|
37 clearblock(p)
|
|
|
38 HEADER *p;
|
|
|
39 {char *s,*t;
|
|
|
40 s = (char *)(p + 1);
|
|
|
41 t = (char *)(p + p->size);
|
|
|
42 while (s < t) *s++ = 0;
|
|
|
43 }
|
|
|
44
|
|
|
45 #define NALLOC 128
|
|
|
46
|
|
|
47 HEADER *morecore(nu)
|
|
|
48 unsigned nu;
|
|
|
49 {char *cp;
|
|
|
50 HEADER *up;
|
|
|
51 int rnu;
|
|
|
52 rnu = NALLOC * ((nu + NALLOC - 1) / NALLOC);
|
|
|
53 cp = sbrk(rnu * sizeof(HEADER));
|
|
|
54 if ((int)cp == -1) return NULL;
|
|
|
55 up = (HEADER *) cp;
|
|
|
56 up->size = rnu;
|
|
|
57 mfree((char *)(up+1));
|
|
|
58 return allocp;
|
|
|
59 }
|
|
|
60
|
|
|
61 #asm
|
|
|
62 sbrk PSHS U
|
|
|
63 LEAU ,S
|
|
|
64
|
|
|
65 LDD heap,Y
|
|
|
66 BNE _mc0
|
|
|
67 BSR initheap
|
|
|
68 _mc0 PSHS D
|
|
|
69 TFR S,D
|
|
|
70 SUBD ,S++
|
|
|
71 CMPD 4,U
|
|
|
72 BCC _mc1
|
|
|
73 LDD #-1
|
|
|
74 LEAS ,U
|
|
|
75 PULS U,PC
|
|
|
76
|
|
|
77 _mc1 LDD 4,U
|
|
|
78 LDX heap,Y
|
|
|
79 LEAX D,X
|
|
|
80 LDD heap,Y
|
|
|
81 STX heap,Y
|
|
|
82 LEAS ,U
|
|
|
83 PULS U,PC
|
|
|
84
|
|
|
85 initheap
|
|
|
86 PSHS U
|
|
|
87 LEAU ,S
|
|
|
88 TFR Y,D
|
|
|
89 ADDD #_GLOBALS
|
|
|
90 STD heap,Y
|
|
|
91 LEAS ,U
|
|
|
92 PULS U,PC
|
|
|
93 #endasm
|
|
|
94
|
|
|
95 mfree(ap)
|
|
|
96 char *ap;
|
|
|
97 {HEADER *p,*q;
|
|
|
98 p = (HEADER *)ap - 1;
|
|
|
99 for (q = allocp; !(p > q && p < q->ptr); q = q->ptr)
|
|
|
100 if (q >= q->ptr && (p > q || p < q->ptr)) break;
|
|
|
101 if (p + p->size == q->ptr)
|
|
|
102 { p->size += q->ptr->size;
|
|
|
103 p->ptr = q->ptr->ptr;
|
|
|
104 }
|
|
|
105 else p->ptr = q->ptr;
|
|
|
106 if (q + q->size == p)
|
|
|
107 { q->size += p->size;
|
|
|
108 q->ptr = p->ptr;
|
|
|
109 }
|
|
|
110 else q->ptr = p;
|
|
|
111 allocp = q;
|
|
|
112 }
|
|
|
113
|
|
|
114 unsigned freesize()
|
|
|
115 {int i;
|
|
|
116 if (!heap) initheap();
|
|
|
117 return ((char *)&i - (char *)heap);
|
|
|
118 }
|
