d3409d5e |
1 | /* -*-c-*- |
2 | * |
3 | * $Id: mparena.c,v 1.1 1999/11/17 18:02:16 mdw Exp $ |
4 | * |
5 | * Allocation and freeing of MP buffers |
6 | * |
7 | * (c) 1999 Straylight/Edgeware |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of Catacomb. |
13 | * |
14 | * Catacomb is free software; you can redistribute it and/or modify |
15 | * it under the terms of the GNU Library General Public License as |
16 | * published by the Free Software Foundation; either version 2 of the |
17 | * License, or (at your option) any later version. |
18 | * |
19 | * Catacomb is distributed in the hope that it will be useful, |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
22 | * GNU Library General Public License for more details. |
23 | * |
24 | * You should have received a copy of the GNU Library General Public |
25 | * License along with Catacomb; if not, write to the Free |
26 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
27 | * MA 02111-1307, USA. |
28 | */ |
29 | |
30 | /*----- Revision history --------------------------------------------------* |
31 | * |
32 | * $Log: mparena.c,v $ |
33 | * Revision 1.1 1999/11/17 18:02:16 mdw |
34 | * New multiprecision integer arithmetic suite. |
35 | * |
36 | */ |
37 | |
38 | /*----- Header files ------------------------------------------------------*/ |
39 | |
40 | #include <stdio.h> |
41 | #include <stdlib.h> |
42 | #include <string.h> |
43 | |
44 | #include <mLib/alloc.h> |
45 | #include <mLib/sub.h> |
46 | |
47 | #include "mparena.h" |
48 | |
49 | /*----- Default allocator -------------------------------------------------*/ |
50 | |
51 | static void *defalloc(mparena *a, size_t sz) { return xmalloc(sz); } |
52 | static void deffree(mparena *a, void *p) { free(p); } |
53 | |
54 | mparena_ops mparena_defops = { defalloc, deffree }; |
55 | |
56 | /*----- Static variables --------------------------------------------------*/ |
57 | |
58 | static mparena arena = { 0, &mparena_defops }; |
59 | |
60 | #define MPARENA_RESOLVE(a) do { \ |
61 | if ((a) == MPARENA_GLOBAL) \ |
62 | (a) = &arena; \ |
63 | } while (0) |
64 | |
65 | /*----- Main code ---------------------------------------------------------*/ |
66 | |
67 | /* --- @tdump@ --- * |
68 | * |
69 | * Arguments: @mparena_node *n@ = pointer to tree node to dump |
70 | * |
71 | * Returns: --- |
72 | * |
73 | * Use: Recursively dumps out the allocation tree. |
74 | */ |
75 | |
76 | static void tdump(mparena_node *n) |
77 | { |
78 | if (!n) |
79 | putchar('*'); |
80 | else { |
81 | putchar('('); |
82 | tdump(n->left); |
83 | printf(", %u, ", n->v[0]); |
84 | tdump(n->right); |
85 | putchar(')'); |
86 | } |
87 | } |
88 | |
89 | /* --- @mparena_create@ --- * |
90 | * |
91 | * Arguments: @mparena *a@ = pointer to arena block |
92 | * |
93 | * Returns: --- |
94 | * |
95 | * Use: Initializes an MP arena so that blocks can be allocated from |
96 | * it. |
97 | */ |
98 | |
99 | void mparena_create(mparena *a) |
100 | { |
101 | a->root = 0; |
102 | a->ops = &mparena_defops; |
103 | } |
104 | |
105 | /* --- @mparena_setops@ --- * |
106 | * |
107 | * Arguments: @mparena *a@ = pointer to arena block |
108 | * @mparena_ops *ops@ = pointer to operations block or null |
109 | * |
110 | * Returns: The previous operations block. |
111 | * |
112 | * Use: Sets or queries the operations attached to an arena. |
113 | */ |
114 | |
115 | mparena_ops *mparena_setops(mparena *a, mparena_ops *ops) |
116 | { |
117 | mparena_ops *o; |
118 | MPARENA_RESOLVE(a); |
119 | o = a->ops; |
120 | if (ops) |
121 | a->ops = ops; |
122 | return (0); |
123 | } |
124 | |
125 | /* --- @mparena_destroy@ --- * |
126 | * |
127 | * Arguments: @mparena *a@ = pointer to arena block |
128 | * |
129 | * Returns: --- |
130 | * |
131 | * Use: Frees an MP arena, and all the vectors held within it. The |
132 | * blocks which are currently allocated can be freed into some |
133 | * other arena. |
134 | */ |
135 | |
136 | static void tfree(mparena *a, mparena_node *n) |
137 | { |
138 | a->ops->free(a, n->v); |
139 | if (n->left) |
140 | tfree(a, n->left); |
141 | if (n->right) |
142 | tfree(a, n->right); |
143 | DESTROY(n); |
144 | } |
145 | |
146 | void mparena_destroy(mparena *a) |
147 | { |
148 | tfree(a, a->root); |
149 | a->root = 0; |
150 | } |
151 | |
152 | /* --- @mpalloc@ --- * |
153 | * |
154 | * Arguments: @mparena *a@ = pointer to arena block |
155 | * @size_t sz@ = number of digits required |
156 | * |
157 | * Returns: Pointer to a suitably sized block. |
158 | * |
159 | * Use: Allocates a lump of data suitable for use as an array of MP |
160 | * digits. |
161 | */ |
162 | |
163 | mpw *mpalloc(mparena *a, size_t sz) |
164 | { |
165 | mparena_node **nn, *n; |
166 | mpw *v; |
167 | |
168 | MPARENA_RESOLVE(a); |
169 | nn = &a->root; |
170 | |
171 | #ifdef notdef |
172 | printf("*** alloc %u\n", sz); |
173 | tdump(a->root); putchar('\n'); |
174 | #endif |
175 | |
176 | /* --- First, find a block which is big enough --- */ |
177 | |
178 | again: |
179 | n = *nn; |
180 | if (!n) { |
181 | v = a->ops->alloc(a, MPWS(sz + 1)); |
182 | v[0] = sz; |
183 | return (v + 1); |
184 | } |
185 | if (n->v[0] < sz) { |
186 | nn = &n->right; |
187 | goto again; |
188 | } |
189 | |
190 | /* --- Now try to find a smaller block which is suitable --- */ |
191 | |
192 | while (n->left && n->left->v[0] >= sz) { |
193 | nn = &n->left; |
194 | n = *nn; |
195 | } |
196 | |
197 | /* --- If the block we've got is still too large, start digging --- */ |
198 | |
199 | if (n->v[0] >= sz * 2) { |
200 | nn = &n->left; |
201 | goto again; |
202 | } |
203 | |
204 | /* --- I've now found a suitable block --- */ |
205 | |
206 | v = n->v; |
207 | |
208 | /* --- Remove this node from the tree --- */ |
209 | |
210 | if (!n->left) |
211 | *nn = n->right; |
212 | else if (!n->right) |
213 | *nn = n->left; |
214 | else { |
215 | mparena_node *left = n->left; |
216 | mparena_node *p = *nn = n->right; |
217 | while (p->left) |
218 | p = p->left; |
219 | p->left = left; |
220 | } |
221 | |
222 | /* --- Get rid of this node now --- */ |
223 | |
224 | DESTROY(n); |
225 | return (v + 1); |
226 | } |
227 | |
228 | /* --- @mpfree@ --- * |
229 | * |
230 | * Arguments: @mparena *a@ = pointer to arena block |
231 | * @mpw *v@ = pointer to allocated vector |
232 | * |
233 | * Returns: --- |
234 | * |
235 | * Use: Returns an MP vector to an arena. It doesn't have to be |
236 | * returned to the arena from which it was allocated. |
237 | */ |
238 | |
239 | void mpfree(mparena *a, mpw *v) |
240 | { |
241 | mparena_node **nn, *n; |
242 | size_t sz = *--v; |
243 | |
244 | MPARENA_RESOLVE(a); |
245 | nn = &a->root; |
246 | |
247 | while (*nn) { |
248 | n = *nn; |
249 | if (n->v[0] > sz) |
250 | nn = &n->left; |
251 | else |
252 | nn = &n->right; |
253 | } |
254 | |
255 | n = CREATE(mparena_node); |
256 | n->left = n->right = 0; |
257 | n->v = v; |
258 | *nn = n; |
259 | |
260 | #ifdef notdef |
261 | printf("*** free %u\n", sz); |
262 | tdump(a->root); putchar('\n'); |
263 | #endif |
264 | } |
265 | |
266 | /*----- That's all, folks -------------------------------------------------*/ |