sys/src/cmd/mk/bufblock.c

   1 #include        "mk.h"
   2
   3 static Bufblock *freelist;
   4 #define QUANTA  4096
   5
   6 Bufblock *
   7 newbuf(void)
   8 {
   9         Bufblock *p;
  10
  11         if (freelist) {
  12                 p = freelist;
  13                 freelist = freelist->next;
  14         } else {
  15                 p = (Bufblock *) Malloc(sizeof(Bufblock));
  16                 p->start = Malloc(QUANTA*sizeof(*p->start));
  17                 p->end = p->start+QUANTA;
  18         }
  19         p->current = p->start;
  20         *p->start = 0;
  21         p->next = 0;
  22         return p;
  23 }
  24
  25 void
  26 freebuf(Bufblock *p)
  27 {
  28         p->next = freelist;
  29         freelist = p;
  30 }
  31
  32 void
  33 growbuf(Bufblock *p)
  34 {
  35         int n;
  36         Bufblock *f;
  37         char *cp;
  38
  39         n = p->end-p->start+QUANTA;
  40                 /* search the free list for a big buffer */
  41         for (f = freelist; f; f = f->next) {
  42                 if (f->end-f->start >= n) {
  43                         memcpy(f->start, p->start, p->end-p->start);
  44                         cp = f->start;
  45                         f->start = p->start;
  46                         p->start = cp;
  47                         cp = f->end;
  48                         f->end = p->end;
  49                         p->end = cp;
  50                         f->current = f->start;
  51                         break;
  52                 }
  53         }
  54         if (!f) {               /* not found - grow it */
  55                 p->start = Realloc(p->start, n);
  56                 p->end = p->start+n;
  57         }
  58         p->current = p->start+n-QUANTA;
  59 }
  60
  61 void
  62 bufcpy(Bufblock *buf, char *cp, int n)
  63 {
  64
  65         while (n--)
  66                 insert(buf, *cp++);
  67 }
  68
  69 void
  70 insert(Bufblock *buf, int c)
  71 {
  72
  73         if (buf->current >= buf->end)
  74                 growbuf(buf);
  75         *buf->current++ = c;
  76 }
  77
  78 void
  79 rinsert(Bufblock *buf, Rune r)
  80 {
  81         int n;
  82
  83         n = runelen(r);
  84         if (buf->current+n > buf->end)
  85                 growbuf(buf);
  86         runetochar(buf->current, &r);
  87         buf->current += n;
  88 }