1cd8169f0Sbostic /*- 2*e049d966Sbostic * Copyright (c) 1980, 1993 3*e049d966Sbostic * The Regents of the University of California. All rights reserved. 46f1350a3Sdist * 5cd8169f0Sbostic * %sccs.include.proprietary.c% 6cd8169f0Sbostic * 7*e049d966Sbostic * @(#)ex_temp.h 8.1 (Berkeley) 06/09/93 86f1350a3Sdist */ 96f1350a3Sdist 10a87d28c0Smark /* 11a87d28c0Smark * The editor uses a temporary file for files being edited, in a structure 12a87d28c0Smark * similar to that of ed. The first block of the file is used for a header 13a87d28c0Smark * block which guides recovery after editor/system crashes. 14a87d28c0Smark * Lines are represented in core by a pointer into the temporary file which 15cde8cdf9Smark * is packed into 16 bits (32 on VMUNIX). All but the low bit index the temp 16cde8cdf9Smark * file; the last is used by global commands. The parameters below control 17cde8cdf9Smark * how much the other bits are shifted left before they index the temp file. 18a87d28c0Smark * Larger shifts give more slop in the temp file but allow larger files 19a87d28c0Smark * to be edited. 20a87d28c0Smark * 21a87d28c0Smark * The editor does not garbage collect the temporary file. When a new 22a87d28c0Smark * file is edited, the temporary file is rather discarded and a new one 23a87d28c0Smark * created for the new file. Garbage collection would be rather complicated 24a87d28c0Smark * in ex because of the general undo, and in any case would require more 25a87d28c0Smark * work when throwing lines away because marks would have be carefully 26a87d28c0Smark * checked before reallocating temporary file space. Said another way, 27a87d28c0Smark * each time you create a new line in the temporary file you get a unique 28a87d28c0Smark * number back, and this is a property used by marks. 29a87d28c0Smark * 30a87d28c0Smark * The following temp file parameters allow 256k bytes in the temporary 31a87d28c0Smark * file. By changing to the numbers in comments you can get 512k. 32cde8cdf9Smark * For VMUNIX you get more than you could ever want. 33cde8cdf9Smark * VMUNIX uses long (32 bit) integers giving much more 34cde8cdf9Smark * space in the temp file and no waste. This doubles core 35cde8cdf9Smark * requirements but allows files of essentially unlimited size to be edited. 36a87d28c0Smark */ 37cde8cdf9Smark #ifndef VMUNIX 38a87d28c0Smark #define BLKMSK 0777 /* 01777 */ 39a87d28c0Smark #define BNDRY 8 /* 16 */ 40a87d28c0Smark #define INCRMT 0200 /* 0100 */ 41a87d28c0Smark #define LBTMSK 0770 /* 0760 */ 42a87d28c0Smark #define NMBLKS 506 /* 1018 */ 43a87d28c0Smark #define OFFBTS 7 /* 6 */ 44a87d28c0Smark #define OFFMSK 0177 /* 077 */ 45a87d28c0Smark #define SHFT 2 /* 3 */ 46cde8cdf9Smark #else 47cde8cdf9Smark #define BLKMSK 077777 48cde8cdf9Smark #define BNDRY 2 49cde8cdf9Smark #define INCRMT 02000 50cde8cdf9Smark #define LBTMSK 01776 51cde8cdf9Smark #define NMBLKS 077770 52cde8cdf9Smark #define OFFBTS 10 53cde8cdf9Smark #define OFFMSK 01777 54cde8cdf9Smark #define SHFT 0 55cde8cdf9Smark #endif 56a87d28c0Smark 57a87d28c0Smark /* 58a87d28c0Smark * The editor uses three buffers into the temporary file (ed uses two 59a87d28c0Smark * and is very similar). These are two read buffers and one write buffer. 60cde8cdf9Smark * Basically, the editor deals with the file as a sequence of BUFSIZ character 61cde8cdf9Smark * blocks. Each block contains some number of lines (and lines 62a87d28c0Smark * can run across block boundaries. 63a87d28c0Smark * 64a87d28c0Smark * New lines are written into the last block in the temporary file 65a87d28c0Smark * which is in core as obuf. When a line is needed which isn't in obuf, 66a87d28c0Smark * then it is brought into an input buffer. As there are two, the choice 67a87d28c0Smark * is to take the buffer into which the last read (of the two) didn't go. 68a87d28c0Smark * Thus this is a 2 buffer LRU replacement strategy. Measurement 69a87d28c0Smark * shows that this saves roughly 25% of the buffer reads over a one 70a87d28c0Smark * input buffer strategy. Since the editor (on our VAX over 1 week) 71a87d28c0Smark * spends (spent) roughly 30% of its time in the system read routine, 72a87d28c0Smark * this can be a big help. 73a87d28c0Smark */ 740be8406aSdist var bool hitin2; /* Last read hit was ibuff2 not ibuff */ 750be8406aSdist var bool ichang2; /* Have actually changed ibuff2 */ 760be8406aSdist var bool ichanged; /* Have actually changed ibuff */ 770be8406aSdist var short iblock; /* Temp file block number of ibuff (or -1) */ 780be8406aSdist var short iblock2; /* Temp file block number of ibuff2 (or -1) */ 790be8406aSdist var short ninbuf; /* Number useful chars left in input buffer */ 800be8406aSdist var short nleft; /* Number usable chars left in output buffer */ 810be8406aSdist var short oblock; /* Temp file block number of obuff (or -1) */ 82cde8cdf9Smark #ifndef VMUNIX 830be8406aSdist var short tline; /* Current temp file ptr */ 84cde8cdf9Smark #else 850be8406aSdist var int tline; 86cde8cdf9Smark #endif 87a87d28c0Smark 880be8406aSdist var char ibuff[BUFSIZ]; 890be8406aSdist var char ibuff2[BUFSIZ]; 900be8406aSdist var char obuff[BUFSIZ]; 91a87d28c0Smark 92a87d28c0Smark /* 93a87d28c0Smark * Structure of the descriptor block which resides 94a87d28c0Smark * in the first block of the temporary file and is 95a87d28c0Smark * the guiding light for crash recovery. 96a87d28c0Smark * 97a87d28c0Smark * As the Blocks field below implies, there are temporary file blocks 98a87d28c0Smark * devoted to (some) image of the incore array of pointers into the temp 99a87d28c0Smark * file. Thus, to recover from a crash we use these indices to get the 100a87d28c0Smark * line pointers back, and then use the line pointers to get the text back. 101a87d28c0Smark * Except for possible lost lines due to sandbagged I/O, the entire 102a87d28c0Smark * file (at the time of the last editor "sync") can be recovered from 103a87d28c0Smark * the temp file. 104a87d28c0Smark */ 105a87d28c0Smark 106a87d28c0Smark /* This definition also appears in expreserve.c... beware */ 107a87d28c0Smark struct header { 108a87d28c0Smark time_t Time; /* Time temp file last updated */ 1090be8406aSdist int Uid; 110cde8cdf9Smark #ifndef VMUNIX 111a87d28c0Smark short Flines; /* Number of lines in file */ 112cde8cdf9Smark #else 113cde8cdf9Smark int Flines; 114cde8cdf9Smark #endif 115a87d28c0Smark char Savedfile[FNSIZE]; /* The current file name */ 116a87d28c0Smark short Blocks[LBLKS]; /* Blocks where line pointers stashed */ 1170be8406aSdist }; 1180be8406aSdist var struct header H; 119a87d28c0Smark 120a87d28c0Smark #define uid H.Uid 121a87d28c0Smark #define flines H.Flines 122a87d28c0Smark #define savedfile H.Savedfile 123a87d28c0Smark #define blocks H.Blocks 124