unroff/src/buffer.c

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2023-02-13 08:45:50 -05:00
/* $Revision: 1.7 $
*/
/* `Buffer' is a dynamically growing, general-purpose buffer data
* structure.
*
* buffer_new(size) -- returns new buffer with initial size `size'
* or some default size if argument is zero
* buffer_delete(b) -- marks a buffer as unused
* buffer_clear(b) -- empties a buffer
* buffer_puts(b,data,len) -- appends data to a buffer, growing it if
* necessary
* buffer_putc(b,c) -- appends a character to a buffer
*/
#include "unroff.h"
static int sizeinc_linear(Buffer *);
static Buffer *first_free;
Buffer *buffer_new(int size) {
Buffer *p;
if (size == 0)
size = 512;
if (first_free) { /* reuse a buffer if there is one */
p = first_free;
first_free = p->next;
if (p->max < size) {
free(p->data);
p->data = safe_malloc(p->max = size);
}
} else {
p = safe_malloc(sizeof *p);
p->data = safe_malloc(size);
p->increment = p->max = size;
p->sizeinc_func = sizeinc_linear;
}
buffer_clear(p);
return p;
}
void buffer_delete(Buffer *p) {
assert(p->size >= 0);
p->size = -1;
p->next = first_free;
first_free = p;
}
void buffer_grow(Buffer *p) {
p->max = p->sizeinc_func(p);
p->data = safe_realloc(p->data, p->max);
}
void buffer_puts(Buffer *p, char *s, int size) {
assert(size >= 0);
while (p->size + size > p->max)
buffer_grow(p);
if (size == 0)
return;
memcpy(p->data+p->size, s, size);
p->size += size;
}
static int sizeinc_linear(Buffer *p) {
return p->max + p->increment;
}