move wip stuff to wip

wip/runlength.c

@@ -0,0 +1,107 @@
+#include <ctype.h> /* isdigit(3) */
+#include <stdio.h> /* fprintf(3), getc(3), putc(3) */
+#include <stdlib.h> /* stdin, stderr, stdout */
+#include <sysexits.h> /* EX_DATAERR, EX_OK */
+
+/* Unicode compatibility coming someday */
+#define GETC getc
+#define PUTC putc
+
+#define NUMBER_TERMINATOR '*'
+
+/* syntax error if a decoding file ends with [char][char] */
+/* if(STRICT) just print it out */
+#define STRICT 0
+
+static int decode(FILE *input, FILE *output){
+	int c[2];
+	unsigned int num;
+	enum{NUMBER_PARSING = 1} state;
+
+	c[0] = EOF;
+
+	/* reading -> (current char == prev char)> number parsing -> reading */
+	while((c[1] = GETC(input)) != EOF)
+		if(state == NUMBER_PARSING){
+			if(isdigit(c[1]))
+				num = num * 10 + c[1] - '0';
+			else if(c[1] == NUMBER_TERMINATOR){
+				for(; num > 0; --num)
+					PUTC(c[0], output);
+				c[0] = EOF; c[1] = EOF;
+				state = 0;
+			}else
+				return EX_DATAERR;
+		}else if(c[1] == c[0]){
+			num = 0;
+			state = NUMBER_PARSING;
+		}else{
+			if(c[0] != EOF)
+				PUTC(c[0], output);
+			c[0] = c[1];
+		}
+
+	if(state == NUMBER_PARSING && !STRICT)
+		/* it doesn't make sense to put this in a loop */
+		{ PUTC(c[0], output); PUTC(c[0], output); }
+	else if(state == NUMBER_PARSING)
+		return EX_DATAERR;
+	else if(c[0] != EOF)
+		PUTC(c[0], output);
+
+	return EX_OK;
+}
+
+static int encode(FILE *input, FILE *output){
+	int c[2];
+	unsigned int num;
+	enum{COUNTING = 1} state;
+
+	/* It was more fun to use gotos than to use sane structure. */
+	for(c[0] = EOF, num = 2, state = 0; ;)
+		if((c[1] = GETC(input)) == EOF){
+			if(state == COUNTING)
+				goto dump;
+			else
+				goto place;
+		}else if(state == COUNTING){
+			if(c[1] != c[0]){
+dump:				PUTC(c[0], output);
+				fprintf(output,
+					"%d%c",
+					num, NUMBER_TERMINATOR
+				);
+				num = 2;
+				state = 0;
+				goto next;
+			}else
+				++num;
+		}else if(c[1] == c[0])
+			state = COUNTING;
+		else{ /* c[1] != c[0] */
+			if(c[0] != EOF) /* c[0] will be EOF at first */
+place:				PUTC(c[0], output);
+next:			if(c[1] == EOF)
+				return EX_OK;
+			c[0] = c[1];
+		}
+}
+
+int main(int argc, char *argv[]){
+	int r;
+
+	if(argc != 1){
+		fprintf(stderr,
+			"Usage: %s\n",
+			argv[0] == NULL ?
+				(f == decode ? "decode" : "encode")
+			: argv[0]
+		);
+		return EX_USAGE;
+	}
+
+	if((r = f(stdin, stdout)) == EX_DATAERR)
+		fprintf(stderr, "%s: syntax error.\n", argv[0]);
+
+	return r;
+}