4.3BSD - /usr/src/ucb/ex/ex_temp.h

   1: /*
   2:  * Copyright (c) 1980 Regents of the University of California.
   3:  * All rights reserved.  The Berkeley software License Agreement
   4:  * specifies the terms and conditions for redistribution.
   5:  *
   6:  *	@(#)ex_temp.h	7.4 (Berkeley) 5/31/85
   7:  */
   8: 
   9: /*
  10:  * The editor uses a temporary file for files being edited, in a structure
  11:  * similar to that of ed.  The first block of the file is used for a header
  12:  * block which guides recovery after editor/system crashes.
  13:  * Lines are represented in core by a pointer into the temporary file which
  14:  * is packed into 16 bits (32 on VMUNIX).  All but the low bit index the temp
  15:  * file; the last is used by global commands.  The parameters below control
  16:  * how much the other bits are shifted left before they index the temp file.
  17:  * Larger shifts give more slop in the temp file but allow larger files
  18:  * to be edited.
  19:  *
  20:  * The editor does not garbage collect the temporary file.  When a new
  21:  * file is edited, the temporary file is rather discarded and a new one
  22:  * created for the new file.  Garbage collection would be rather complicated
  23:  * in ex because of the general undo, and in any case would require more
  24:  * work when throwing lines away because marks would have be carefully
  25:  * checked before reallocating temporary file space.  Said another way,
  26:  * each time you create a new line in the temporary file you get a unique
  27:  * number back, and this is a property used by marks.
  28:  *
  29:  * The following temp file parameters allow 256k bytes in the temporary
  30:  * file.  By changing to the numbers in comments you can get 512k.
  31:  * For VMUNIX you get more than you could ever want.
  32:  * VMUNIX uses long (32 bit) integers giving much more
  33:  * space in the temp file and no waste.  This doubles core
  34:  * requirements but allows files of essentially unlimited size to be edited.
  35:  */
  36: #ifndef VMUNIX
  37: #define BLKMSK  0777        /* 01777 */
  38: #define BNDRY   8       /* 16 */
  39: #define INCRMT  0200        /* 0100 */
  40: #define LBTMSK  0770        /* 0760 */
  41: #define NMBLKS  506     /* 1018 */
  42: #define OFFBTS  7       /* 6 */
  43: #define OFFMSK  0177        /* 077 */
  44: #define SHFT    2       /* 3 */
  45: #else
  46: #define BLKMSK  077777
  47: #define BNDRY   2
  48: #define INCRMT  02000
  49: #define LBTMSK  01776
  50: #define NMBLKS  077770
  51: #define OFFBTS  10
  52: #define OFFMSK  01777
  53: #define SHFT    0
  54: #endif
  55: 
  56: /*
  57:  * The editor uses three buffers into the temporary file (ed uses two
  58:  * and is very similar).  These are two read buffers and one write buffer.
  59:  * Basically, the editor deals with the file as a sequence of BUFSIZ character
  60:  * blocks.  Each block contains some number of lines (and lines
  61:  * can run across block boundaries.
  62:  *
  63:  * New lines are written into the last block in the temporary file
  64:  * which is in core as obuf.  When a line is needed which isn't in obuf,
  65:  * then it is brought into an input buffer.  As there are two, the choice
  66:  * is to take the buffer into which the last read (of the two) didn't go.
  67:  * Thus this is a 2 buffer LRU replacement strategy.  Measurement
  68:  * shows that this saves roughly 25% of the buffer reads over a one
  69:  * input buffer strategy.  Since the editor (on our VAX over 1 week)
  70:  * spends (spent) roughly 30% of its time in the system read routine,
  71:  * this can be a big help.
  72:  */
  73: var bool    hitin2;     /* Last read hit was ibuff2 not ibuff */
  74: var bool    ichang2;    /* Have actually changed ibuff2 */
  75: var bool    ichanged;   /* Have actually changed ibuff */
  76: var short   iblock;     /* Temp file block number of ibuff (or -1) */
  77: var short   iblock2;    /* Temp file block number of ibuff2 (or -1) */
  78: var short   ninbuf;     /* Number useful chars left in input buffer */
  79: var short   nleft;      /* Number usable chars left in output buffer */
  80: var short   oblock;     /* Temp file block number of obuff (or -1) */
  81: #ifndef VMUNIX
  82: var short   tline;      /* Current temp file ptr */
  83: #else
  84: var int tline;
  85: #endif
  86: 
  87: var char    ibuff[BUFSIZ];
  88: var char    ibuff2[BUFSIZ];
  89: var char    obuff[BUFSIZ];
  90: 
  91: /*
  92:  * Structure of the descriptor block which resides
  93:  * in the first block of the temporary file and is
  94:  * the guiding light for crash recovery.
  95:  *
  96:  * As the Blocks field below implies, there are temporary file blocks
  97:  * devoted to (some) image of the incore array of pointers into the temp
  98:  * file.  Thus, to recover from a crash we use these indices to get the
  99:  * line pointers back, and then use the line pointers to get the text back.
 100:  * Except for possible lost lines due to sandbagged I/O, the entire
 101:  * file (at the time of the last editor "sync") can be recovered from
 102:  * the temp file.
 103:  */
 104: 
 105: /* This definition also appears in expreserve.c... beware */
 106: struct  header {
 107:     time_t  Time;           /* Time temp file last updated */
 108:     int Uid;
 109: #ifndef VMUNIX
 110:     short   Flines;         /* Number of lines in file */
 111: #else
 112:     int Flines;
 113: #endif
 114:     char    Savedfile[FNSIZE];  /* The current file name */
 115:     short   Blocks[LBLKS];      /* Blocks where line pointers stashed */
 116: };
 117: var struct  header H;
 118: 
 119: #define uid     H.Uid
 120: #define flines      H.Flines
 121: #define savedfile   H.Savedfile
 122: #define blocks      H.Blocks

Defined variables

Defined struct's

Defined macros

Usage of this include