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@
% Copyright (C) 1987 Princeton University
%
% This file is part of CWEB.
% This program by Silvio Levy is based on a program by D. E. Knuth.
% It is distributed WITHOUT ANY WARRANTY, express or implied.
% $Revision 1.1$ -- Dec 1987
%
% Please send comments, suggestions, etc. to levy@princeton.
%
Here's stuff from the file |"common.web"| that has to be included in
|"tangle.web"| and |"weave.web"|.

General stuff:

@d tangle 0
@d weave 1

@<Common code for \.{WEAVE} and \.{TANGLE}@>=
typedef short boolean;
typedef char unsigned eight_bits;
extern boolean program; /* \.{WEAVE} or \.{TANGLE}? */
extern int phase; /* which phase are we in? */

@ @<Include files@>=
#include <stdio.h>

@ Code related to the character set:
@d and_and 04 /* `\.{\&\&}' */
@d tab_mark 011 /* ASCII code used as tab-skip */
@d line_feed 012 /* ASCII code thrown away at end of line */
@d form_feed 014 /* ASCII code used at end of page */
@d carriage_return 015 /* ASCII code used at end of line */
@d gt_gt 020 /* `\.{>>}'; this doesn't exist in MIT */
@d lt_lt 022 /* `\.{<<}'; this doesn't exist in MIT */
@d plus_plus 013 /* `\.{++}'; this corresponds to MIT's up-arrow */
@d minus_minus 01 /* `\.{--}'; this corresponds to MIT's down-arrow */
@d minus_gt 031 /* `\.{->}' */
@d not_eq 032 /* `\.{!=}' */
@d lt_eq 034 /* `\.{<=}' */
@d gt_eq 035 /* `\.{>=}' */
@d eq_eq 036 /* `\.{==}' */
@d or_or 037 /* `\.{\v\v}' */

@<Common code...@>=
typedef char ASCII; /* type of characters inside \.{WEB} */
typedef char outer_char; /* type of characters outside \.{WEB} */
extern ASCII xord[]; /* specifies conversion of input characters */
extern outer_char xchr[]; /* specifies conversion of output characters */
ASCII mod_text[longest_name+1]; /* name being sought for */
ASCII *mod_text_end = mod_text+longest_name; /* end of |mod_text| */
ASCII *id_first; /* where the current identifier begins in the buffer */
ASCII *id_loc; /* just after the current identifier in the buffer */

@ Code related to input routines:

@<Common code...@>=
extern ASCII buffer[]; /* where each line of input goes */
extern ASCII *buffer_end; /* end of |buffer| */
extern ASCII *loc; /* points to the next character to be read from the buffer*/
extern ASCII *limit; /* points to the last character in the buffer */

@ Code related to identifier and module name storage:
@d length(c) (c+1)->byte_start-(c)->byte_start /* the length of a name */
@d print_id(c) ASCII_write((c)->byte_start,length((c)))
  /* print identifier or module name */
@d llink link /* left link in binary search tree for module names */
@d rlink dummy.Rlink /* right link in binary search tree for module names */
@d root name_dir->rlink /* the root of the binary search tree
  for module names */

@<Common code...@>=
typedef struct name_info {
  ASCII *byte_start; /* beginning of the name in |byte_mem| */
  struct name_info *link;
  union {
    struct name_info *Rlink; /* right link in binary search tree for module
      names */  
    char Ilk; /* used by identifiers in \.{WEAVE} only */
  } dummy;
  ASCII *equiv_or_xref; /* info corresponding to names */
} name_info; /* contains information about an identifier or module name */
typedef name_info *name_pointer; /* pointer into array of |name_info|s */
typedef name_pointer *hash_pointer;
extern ASCII byte_mem[]; /* characters of names */
extern ASCII *byte_mem_end; /* end of |byte_mem| */
extern name_info name_dir[]; /* information about names */
extern name_pointer name_dir_end; /* end of |name_dir| */
extern name_pointer name_ptr; /* first unused position in |byte_start| */
extern ASCII *byte_ptr; /* first unused position in |byte_mem| */
extern name_pointer hash[]; /* heads of hash lists */
extern hash_pointer hash_end; /* end of |hash| */
extern hash_pointer h; /* index into hash-head array */
extern name_pointer id_lookup(); /* looks up a string in the identifier table */
extern name_pointer mod_lookup(); /* finds module name */
extern name_pointer prefix_lookup(); /* finds module name given a prefix */

@ Code related to error handling:
@d spotless 0 /* |history| value for normal jobs */
@d harmless_message 1 /* |history| value when non-serious info was printed */
@d error_message 2 /* |history| value when an error was noted */
@d fatal_message 3 /* |history| value when we had to stop prematurely */
@d mark_harmless {if (history==spotless) history=harmless_message;}
@d mark_error history=error_message
@d confusion(s) fatal("! This can't happen: ",s)
@d fatal(s1,s2) {
  printf(s1); err_print(s2);
  history=fatal_message; wrap_up();
}
@d overflow(string) {
  printf("\n! Sorry, %s capacity exceeded",string); fatal("","");
}

@<Common...@>=
extern history; /* indicates how bad this run was */

@ Code related to file handling:
@f line x /* make |line| an unreserved word */
@d max_file_name_length 60
@d cur_file file[include_depth] /* current file */
@d cur_file_name file_name[include_depth] /* current file name */
@d web_file_name file_name[0] /* main source file name */
@d cur_line line[include_depth] /* number of current line in current file */

@<Common code...@>=
extern include_depth; /* current level of nesting */
extern FILE *file[]; /* stack of non-change files */
extern FILE *change_file; /* change file */
extern char C_file_name[]; /* name of |C_file| */
extern char tex_file_name[]; /* name of |tex_file| */
extern char file_name[][max_file_name_length];
  /* stack of non-change file names */
extern char change_file_name[]; /* name of change file */
extern line[]; /* number of current line in the stacked files */
extern change_line; /* number of current line in change file */
extern boolean input_has_ended; /* if there is no more input */
extern boolean changing; /* if the current line is from |change_file| */

@ Code related to module numbers:
@<Common code...@>=
typedef unsigned short sixteen_bits;
extern sixteen_bits module_count; /* the current module number */
extern boolean changed_module[]; /* is the module changed? */
extern boolean print_where; /* tells \.{TANGLE} to print line and file info */

@ Code related to command line arguments:
@<Common code...@>=
extern int argc; /* copy of |ac| parameter to |main| */
extern char **argv; /* copy of |av| parameter to |main| */
extern no_xref; /* should \.{WEAVE} print an index? */

@ Code relating to output:
@d update_terminal fflush(stdout) /* empty the terminal output buffer */
@d new_line putchar('\n') @d putxchar putchar
@d ASCII_write(a,b) fflush(stdout), write(1,a,b) /* write on the standard output */
@d line_write(c) write(fileno(C_file),c) /* write on the C output file */
@d C_printf(c,a) fprintf(C_file,c,a)
@d C_putc(c) putc(c,C_file)

@<Common code...@>=
extern FILE *C_file; /* where output of \.{TANGLE} goes */
extern FILE *tex_file; /* where output of \.{WEAVE} goes */
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