From 39f42c4f391af09dcfb3fb0272534caec26495f5 Mon Sep 17 00:00:00 2001
From: WormHeamer
Date: Mon, 29 Sep 2025 00:44:28 -0400
Subject: add opt.h

---
 opt.h | 86 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 86 insertions(+)
 create mode 100644 opt.h

diff --git a/opt.h b/opt.h
new file mode 100644
index 0000000..0971112
--- /dev/null
+++ b/opt.h
@@ -0,0 +1,86 @@
+#ifndef OPT_H
+#define OPT_H
+
+#define OPT_ARG            1
+#define OPT_AT_END         0
+#define OPT_ERR_NO_PARAM  -1
+#define OPT_ERR_BAD_OPT   -2
+
+#define OPTF_MID_SHORT     1
+#define OPTF_IGNORE        2
+#define OPTF_NO_PRINT_ERR  4
+
+/* fmt is a set of short option chars, preceded by : if they accept an
+ * argument, followed by [foo] for a corresponding long option name. */
+
+int opt_next(int *optf, int *argc, const char ***argv, const char *fmt);
+
+#ifdef OPT_IMPL
+
+#include <stdio.h>
+#include <string.h>
+#include <assert.h>
+
+int opt_next(int *optf, int *argc, const char ***argv, const char *fmt) {
+	if (~*optf & OPTF_MID_SHORT) {
+		*argv += 1, *argc -= 1;
+		if (*argc < 1) return OPT_AT_END;
+	}
+	if (*optf & OPTF_IGNORE) return OPT_ARG;
+
+	int is_long = 0;
+	if (~*optf & OPTF_MID_SHORT) {
+		if ((**argv)[0] != '-') return OPT_ARG;
+		is_long = (**argv)[1] == '-';
+		if (is_long && !(**argv)[2]) {
+			*optf |= OPTF_IGNORE;
+			return opt_next(optf, argc, argv, fmt);
+		}
+	}
+
+	const char *opt = **argv + is_long + !(*optf & OPTF_MID_SHORT);
+	const char *opt_end = is_long ? strchr(opt, '=') : opt + 1;
+	if (!opt_end) opt_end = opt + strlen(opt);
+	unsigned opt_len = opt_end - opt;
+
+	int opt_arg = 0, match = 0;
+	char opt_char = '\0';
+	while (*fmt && !match) {
+		opt_arg = (*fmt == ':');
+		if (opt_arg) fmt++;
+		opt_char = *fmt++;
+		assert(opt_char);
+		match = !is_long && *opt == opt_char;
+		if (*fmt == '[') {
+			const char *rt = strchr(++fmt, ']');
+			assert(rt);
+			match |= is_long && rt-fmt == opt_len && !memcmp(opt, fmt, opt_len);
+			fmt = rt + 1;
+		}
+	}
+
+	*optf &= ~OPTF_MID_SHORT;
+	if (match && opt_arg) {
+		if (*opt_end) {
+			**argv = opt_end + is_long;
+		} else {
+			*argv += 1, *argc -= 1;
+			if (*argc > 0) return opt_char;
+			if (~*optf & OPTF_NO_PRINT_ERR) {
+				fprintf(stderr, "option '%.*s' expected parameter, but none given\n", opt_len, opt);
+			}
+			return OPT_ERR_NO_PARAM;
+		}
+	} else if (!is_long && *opt_end) {
+		*optf |= OPTF_MID_SHORT;
+		**argv = opt_end;
+	}
+
+	if (!match && ~*optf & OPTF_NO_PRINT_ERR) {
+		fprintf(stderr, "unrecognized option '%.*s'\n", opt_len, opt);
+	}
+	return match ? opt_char : OPT_ERR_BAD_OPT;
+}
+
+#endif
+#endif
-- 
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