projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| b2e575b2 JB |
1 | /* Copyright (c) 1985 Regents of the University of California */ |
| 2 | ||
| 3 | /* | |
| 4 | * These routines are for faster tag lookup. They support the binary | |
| 5 | * search used in tagfind() instead of the linear search. The speedup | |
| 6 | * is quite noticable looking for a tag at the end of a long tags | |
| 7 | * file. Define FASTTAG in the Makefile to use these routines. | |
| 8 | */ | |
| 9 | ||
| 10 | #ifdef FASTTAG | |
| 11 | #ifndef lint | |
| 5a6c967e | 12 | static char *sccsid = "@(#)ex_tagio.c 7.4 (Berkeley) %G%"; |
| b2e575b2 JB |
13 | #endif |
| 14 | ||
| 5a6c967e | 15 | #ifndef vms |
| b2e575b2 | 16 | #include <sys/file.h> |
| 5a6c967e CH |
17 | #else |
| 18 | #include <file.h> | |
| 19 | #endif | |
| b2e575b2 JB |
20 | #include "ex.h" |
| 21 | ||
| 22 | static long offset = -1; | |
| 23 | static long block = -1; | |
| 24 | static int bcnt = 0; | |
| 25 | static int b_size = MAXBSIZE; | |
| 26 | static char *ibuf; | |
| 27 | ||
| 28 | topen(file, buf) | |
| 29 | char *file, *buf; | |
| 30 | { | |
| 31 | int fd; | |
| 32 | struct stat statb; | |
| 33 | ||
| 34 | offset = -1; | |
| 35 | block = -1; | |
| 36 | if ((fd = open(file, O_RDONLY, 0)) < 0) | |
| 37 | return(-1); | |
| 38 | if (fstat(fd, &statb) < 0) { | |
| 39 | (void)close(fd); | |
| 40 | return(-1); | |
| 41 | } | |
| 42 | ibuf = buf; | |
| 43 | b_size = statb.st_blksize; | |
| 44 | return(fd); | |
| 45 | } | |
| 46 | ||
| 47 | tseek(fd, off) | |
| 48 | int fd; | |
| 49 | long off; | |
| 50 | { | |
| 51 | int nblock; | |
| 52 | ||
| 53 | nblock = off / b_size * b_size; | |
| 54 | offset = off % b_size; | |
| 55 | if (nblock == block) | |
| 56 | return(0); | |
| 57 | block = nblock; | |
| 58 | if (lseek(fd, nblock, L_SET) < 0) | |
| 59 | return(-1); | |
| 60 | if ((bcnt = read(fd, ibuf, b_size)) < 0) | |
| 61 | return(-1); | |
| 62 | return(0); | |
| 63 | } | |
| 64 | ||
| 65 | tgets(buf, cnt, fd) | |
| 66 | register char *buf; | |
| 67 | int cnt; | |
| 68 | int fd; | |
| 69 | { | |
| 70 | register char *cp; | |
| 71 | register cc; | |
| 72 | ||
| 73 | cc = offset; | |
| 74 | if (cc == -1) { | |
| 75 | if ((bcnt = read(fd, ibuf, b_size)) <= 0) | |
| 76 | return (NULL); | |
| 77 | cc = 0; | |
| 78 | block = 0; | |
| 79 | } | |
| 80 | if (bcnt == 0) /* EOF */ | |
| 81 | return(NULL); | |
| 82 | cp = ibuf + cc; | |
| 83 | while (--cnt > 0) { | |
| 84 | if (++cc > bcnt) { | |
| fa104d3b | 85 | block += b_size; |
| b2e575b2 JB |
86 | if ((bcnt = read(fd, ibuf, b_size)) <= 0) { |
| 87 | offset = cc; | |
| 88 | return (NULL); | |
| 89 | } | |
| b2e575b2 JB |
90 | cp = ibuf; |
| 91 | cc = 1; | |
| 92 | } | |
| 93 | if ((*buf++ = *cp++) == '\n') | |
| 94 | break; | |
| 95 | } | |
| 96 | *--buf = NULL; | |
| 97 | offset = cc; | |
| 98 | return(1); | |
| 99 | } | |
| 100 | ||
| 101 | tclose(fd) | |
| 102 | int fd; | |
| 103 | { | |
| 104 | (void)close(fd); | |
| 105 | offset = -1; | |
| 106 | block = -1; | |
| 107 | bcnt = 0; | |
| 108 | } | |
| 109 | #endif |