Start shared abstraction target

1 files changed, 71 insertions, 0 deletions

diff --git a/src/targets/bblc.c b/src/targets/bblc.c
new file mode 100644
index 0000000..555d400
--- /dev/null
+++ b/src/targets/bblc.c
@@ -0,0 +1,71 @@
+// Copyright (c) 2024, Marvin Borner <dev@marvinborner.de>
+// SPDX-License-Identifier: MIT
+
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+
+#include <target.h>
+#include <parse.h>
+#include <log.h>
+
+static void write_bit(char val, FILE *file, char *byte, int *bit)
+{
+	if (*bit > 7) { // flush byte
+		fwrite(byte, 1, 1, file);
+		*byte = 0;
+		*bit = 0;
+	}
+
+	// TODO: which endianness should be default?
+	if (val)
+		*byte |= 1UL << *bit;
+	/* *byte |= 1UL << (7 - *bit); */
+	(*bit)++;
+}
+
+static void fprint_bblc(struct term *term, struct bloc_parsed *bloc, FILE *file,
+			char *byte, int *bit)
+{
+	switch (term->type) {
+	case ABS:
+		write_bit(0, file, byte, bit);
+		write_bit(0, file, byte, bit);
+		fprint_bblc(term->u.abs.term, bloc, file, byte, bit);
+		break;
+	case APP:
+		write_bit(0, file, byte, bit);
+		write_bit(1, file, byte, bit);
+		fprint_bblc(term->u.app.lhs, bloc, file, byte, bit);
+		fprint_bblc(term->u.app.rhs, bloc, file, byte, bit);
+		break;
+	case VAR:
+		for (int i = 0; i <= term->u.var.index; i++)
+			write_bit(1, file, byte, bit);
+		write_bit(0, file, byte, bit);
+		break;
+	case REF:
+		if (term->u.ref.index + 1 >= bloc->length)
+			fatal("invalid ref index %ld\n", term->u.ref.index);
+		fprint_bblc(bloc->entries[bloc->length - term->u.ref.index - 2],
+			    bloc, file, byte, bit);
+		break;
+	default:
+		fatal("invalid type %d\n", term->type);
+	}
+}
+
+static void write_bblc(struct bloc_parsed *bloc, FILE *file)
+{
+	char byte = 0;
+	int bit = 0;
+	fprint_bblc(bloc->entries[bloc->length - 1], bloc, file, &byte, &bit);
+
+	if (bit)
+		fwrite(&byte, 1, 1, file);
+}
+
+struct target_spec target_bblc = {
+	.name = "bblc",
+	.exec = write_bblc,
+};