shithub: pdffs

ref: a01e30542bfd8d8e1e307e71f4600619a18cacd1
dir: /f_ascii85.c/

#include <u.h>
#include <libc.h>
#include "pdf.h"

/* 7.4.3 ASCII85Decode filter */

static int
flreadall(void *aux, Buffer *bi, Buffer *bo)
{
	uchar *in, c[4];
	int i, j, insz;
	u32int x;

	USED(aux);

	in = bufdata(bi, &insz);
	for(i = 0; i < insz;){
		if(isws(in[i])){
			i++;
			continue;
		}

		if(in[i] == 'z'){
			x = 0;
			i++;
		}else{
			for(x = 0, j = 0; j < 5; j++, i++){
				if(in[i] < '!' || in[i] > 'u'){
					werrstr("invalid ascii85 char 0x%02x", in[i]);
					return -1;
				}
				x = x*85 + ((i < insz ? in[i] : 'u') - '!');
			}
		}
		c[0] = x >> 24;
		c[1] = x >> 16;
		c[2] = x >> 8;
		c[3] = x;
		bufput(bo, c, 4);
	}
	bi->off = bi->sz;

	return 0;
}

Filter filterASCII85 = {
	.name = "ASCII85Decode",
	.readall = flreadall,
};