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990bee10 | 1 | /* $Id: pushback.c,v 1.1 2000/12/09 03:08:23 apbianco Exp $ |
bd8757b3 APB |
2 | |
3 | $Log: pushback.c,v $ | |
990bee10 KG |
4 | Revision 1.1 2000/12/09 03:08:23 apbianco |
5 | 2000-12-08 Alexandre Petit-Bianco <apbianco@cygnus.com> | |
6 | ||
7 | * fastjar: Imported. | |
8 | ||
bd8757b3 APB |
9 | Revision 1.2 2000/08/23 19:42:17 cory |
10 | Added support for more Unix platforms. The following code has been hacked | |
11 | to work on AIX, Solaris, True 64, and HP-UX. | |
12 | Added bigendian check. Probably works on most big and little endian platforms | |
13 | now. | |
14 | ||
15 | Revision 1.1.1.1 1999/12/06 03:09:13 toast | |
16 | initial checkin.. | |
17 | ||
18 | ||
19 | ||
20 | Revision 1.1 1999/05/10 08:32:37 burnsbr | |
21 | Initial revision | |
22 | ||
23 | */ | |
24 | ||
25 | /* | |
26 | pushback.c - code for a pushback buffer to handle file I/O | |
27 | Copyright (C) 1999 Bryan Burns | |
28 | ||
29 | This program is free software; you can redistribute it and/or | |
30 | modify it under the terms of the GNU General Public License | |
31 | as published by the Free Software Foundation; either version 2 | |
32 | of the License, or (at your option) any later version. | |
33 | ||
34 | This program is distributed in the hope that it will be useful, | |
35 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
36 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
37 | GNU General Public License for more details. | |
38 | ||
39 | You should have received a copy of the GNU General Public License | |
40 | along with this program; if not, write to the Free Software | |
41 | Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
42 | */ | |
43 | ||
44 | #include <unistd.h> | |
45 | #include <string.h> | |
46 | #include <stdio.h> | |
47 | ||
48 | #include "jartool.h" | |
49 | #include "pushback.h" | |
50 | ||
bd8757b3 APB |
51 | void pb_init(pb_file *pbf, int fd){ |
52 | pbf->fd = fd; | |
53 | pbf->next = pbf->pb_buff; | |
54 | pbf->buff_amt = 0; | |
55 | } | |
56 | ||
57 | int pb_push(pb_file *pbf, void *buff, int amt){ | |
58 | int in_amt; | |
59 | int wrap = 0; | |
60 | ||
61 | #ifdef DEBUG | |
62 | printf("%d bytes being pushed back to the buffer\n", amt); | |
63 | #endif | |
64 | ||
65 | /* determine how much we can take */ | |
66 | if((RDSZ - pbf->buff_amt) < amt) | |
67 | in_amt = RDSZ - pbf->buff_amt; | |
68 | else | |
69 | in_amt = amt; | |
70 | ||
71 | if(in_amt == 0) | |
72 | return 0; | |
73 | ||
74 | /* figure out if we need to wrap around, and if so, by how much */ | |
75 | if(((pbf->pb_buff + RDSZ) - pbf->next) < in_amt) | |
76 | wrap = in_amt - ((pbf->pb_buff + RDSZ) - pbf->next); | |
77 | ||
78 | /* write everything up til the end of the buffer */ | |
79 | memcpy(pbf->next, buff, (in_amt - wrap)); | |
80 | ||
81 | /* finish writing what's wrapped around */ | |
82 | memcpy(pbf->pb_buff, ((char *)buff + (in_amt - wrap)), wrap); | |
83 | ||
84 | /* update the buff_amt field */ | |
85 | pbf->buff_amt += in_amt; | |
86 | ||
87 | #ifdef DEBUG | |
88 | printf("%d bytes we can't accept\n", (amt - in_amt)); | |
89 | #endif | |
90 | ||
91 | return in_amt; | |
92 | } | |
93 | ||
94 | ||
95 | int pb_read(pb_file *pbf, void *buff, int amt){ | |
96 | int out_amt = 0; | |
97 | int wrap = 0; | |
98 | void *bp = buff; | |
99 | int tmp; | |
100 | ||
101 | #ifdef DEBUG | |
102 | printf("%d bytes requested from us\n", amt); | |
103 | #endif | |
104 | while(out_amt < amt){ | |
105 | /* if our push-back buffer contains some data */ | |
106 | if(pbf->buff_amt > 0){ | |
107 | ||
108 | #ifdef DEBUG | |
109 | printf("giving data from buffer\n"); | |
110 | #endif | |
111 | ||
112 | /* calculate how much we can actually give the caller */ | |
113 | if( (amt - out_amt) < pbf->buff_amt ) | |
114 | tmp = (amt - out_amt); | |
115 | else | |
116 | tmp = pbf->buff_amt; | |
117 | ||
118 | /* Determine if we're going to need to wrap around the buffer */ | |
119 | if(tmp > ((pbf->pb_buff + RDSZ) - pbf->next)) | |
120 | wrap = tmp - ((pbf->pb_buff + RDSZ) - pbf->next); | |
121 | ||
122 | memcpy(bp, pbf->next, (tmp - wrap)); | |
123 | bp = &(((char *)bp)[tmp - wrap]); | |
124 | ||
125 | /* If we need to wrap, read from the start of the buffer */ | |
126 | if(wrap > 0){ | |
127 | memcpy(bp, pbf->pb_buff, wrap); | |
128 | bp = &(((char *)bp)[wrap]); | |
129 | } | |
130 | ||
131 | /* update the buff_amt field */ | |
132 | pbf->buff_amt -= tmp; | |
133 | pbf->next += tmp; | |
134 | ||
135 | #ifdef DEBUG | |
136 | printf("%d bytes remaining in buffer\n", pbf->buff_amt); | |
137 | #endif | |
138 | ||
139 | /* if the buffer is empty, reset the next header to the front of the | |
140 | buffer so subsequent pushbacks/reads won't have to wrap */ | |
141 | if(pbf->buff_amt == 0) | |
142 | pbf->next = pbf->pb_buff; | |
143 | ||
144 | out_amt += tmp; | |
145 | ||
146 | } else { | |
147 | #ifdef DEBUG | |
148 | printf("Reading from file..\n"); | |
149 | #endif | |
150 | ||
151 | /* The pushback buffer was empty, so we just need to read from the file */ | |
152 | tmp = read(pbf->fd, bp, (amt - out_amt)); | |
153 | if(tmp == 0) | |
154 | break; | |
155 | else | |
156 | out_amt += tmp; | |
157 | ||
158 | bp = &(((char *)bp)[tmp]); | |
159 | } | |
160 | } | |
161 | ||
162 | #ifdef DEBUG | |
163 | printf("managed to read %d bytes\n", out_amt); | |
164 | #endif | |
165 | return out_amt; | |
166 | } |