tti.c - plan9port - [fork] Plan 9 from user space
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       ---
       tti.c (1190B)
       ---
            1 /* ti.c: classify line intersections */
            2 # include "t.h"
            3 /* determine local environment for intersections */
            4 
            5 int
            6 interv(int i, int c)
            7 {
            8         int        ku, kl;
            9 
           10         if (c >= ncol || c == 0) {
           11                 if (dboxflg) {
           12                         if (i == 0)
           13                                 return(BOT);
           14                         if (i >= nlin)
           15                                 return(TOP);
           16                         return(THRU);
           17                 }
           18                 if (c >= ncol)
           19                         return(0);
           20         }
           21         ku = i > 0 ? lefdata(i - 1, c) : 0;
           22         if (i + 1 >= nlin && allh(i))
           23                 kl = 0;
           24         else
           25                 kl = lefdata(allh(i) ? i + 1 : i, c);
           26         if (ku == 2 && kl == 2)
           27                 return(THRU);
           28         if (ku == 2)
           29                 return(TOP);
           30         if (kl == BOT)
           31                 return(2);
           32         return(0);
           33 }
           34 
           35 
           36 int
           37 interh(int i, int c)
           38 {
           39         int        kl, kr;
           40 
           41         if (fullbot[i] == '=' || (dboxflg && (i == 0 || i >= nlin - 1))) {
           42                 if (c == ncol)
           43                         return(LEFT);
           44                 if (c == 0)
           45                         return(RIGHT);
           46                 return(THRU);
           47         }
           48         if (i >= nlin)
           49                 return(0);
           50         kl = c > 0 ? thish (i, c - 1) : 0;
           51         if (kl <= 1 && i > 0 && allh(up1(i)))
           52                 kl = c > 0 ? thish(up1(i), c - 1) : 0;
           53         kr = thish(i, c);
           54         if (kr <= 1 && i > 0 && allh(up1(i)))
           55                 kr = c > 0 ? thish(up1(i), c) : 0;
           56         if (kl == '=' && kr ==  '=')
           57                 return(THRU);
           58         if (kl == '=')
           59                 return(LEFT);
           60         if (kr == '=')
           61                 return(RIGHT);
           62         return(0);
           63 }
           64 
           65 
           66 int
           67 up1(int i)
           68 {
           69         i--;
           70         while (instead[i] && i > 0)
           71                 i--;
           72         return(i);
           73 }