From 2be1815c9a6b0c41fe11d0fc311f46ac7d99088c Mon Sep 17 00:00:00 2001
From: Lukas Krickl <lukas@krickl.dev>
Date: Wed, 31 Dec 2025 06:17:29 +0100
Subject: [PATCH] ulas: Added line escaping

Lines can now be escape using '\'.
When the last printable character of a line is '\' the next line is read
before executing the preprocessor. This allows breaking up lines into
more readable variants.
---
 TODO.md             |   1 -
 makefile            |   1 +
 src/test.c          |   1 +
 src/ulas.c          |  56 +++++++++++++++++++++++++++++++++++++++++---
 tests/multiline.bin | Bin 0 -> 17 bytes
 tests/multiline.s   |  17 ++++++++++++++
 6 files changed, 72 insertions(+), 4 deletions(-)
 create mode 100644 tests/multiline.bin
 create mode 100644 tests/multiline.s

diff --git a/TODO.md b/TODO.md
index 4820496..cd055f7 100644
--- a/TODO.md
+++ b/TODO.md
@@ -9,7 +9,6 @@
 - Assert `.section` in full test
 - Add `.bank.` directive allowing users to set the current bank number (ulas.bank) which can be used for symbol files.
 - Allow nested begin and end scope calls
-- Add `forth-like` mode. This mode should allow defining words similar to forth. It should have a built-in word for `assembly output` that can be implemented by the user.
 - Add `.extern` directive allowing the user to define external labels
 - Add `.scope` for `.def` and `.de.` variables
 - Add `#cop n, ...` preprocessor directive. It should work just like .rep but just insert the line n times into the source code and then preprocess the result.
diff --git a/makefile b/makefile
index 7badfd8..4b66e38 100644
--- a/makefile
+++ b/makefile
@@ -52,4 +52,5 @@ install:
 
 buildtests: bin 
 	./$(NAME) tests/t0.s -D ULAS_PREDEF -l - -o tests/t0.bin
+	./$(NAME) tests/multiline.s -D ULAS_PREDEF -l - -o tests/multiline.bin
 	./$(NAME) tests/t0.bin -d - -o tests/t0_dasm.s
diff --git a/src/test.c b/src/test.c
index 0fa1c23..553d5f8 100644
--- a/src/test.c
+++ b/src/test.c
@@ -421,6 +421,7 @@ void test_full_asm(void) {
   TESTBEGIN("testfullasm");
 
   ASSERT_FULL_ASM(0, "tests/t0.s", "tests/t0.bin");
+  ASSERT_FULL_ASM(0, "tests/multiline.s", "tests/multiline.bin");
 
   TESTEND("testfullasm");
 }
diff --git a/src/ulas.c b/src/ulas.c
index 19894ba..9f1d3d8 100644
--- a/src/ulas.c
+++ b/src/ulas.c
@@ -1290,11 +1290,61 @@ found:
   return ULAS_PPDIR_NONE;
 }
 
+// checks if the last printable char in a string is '\'
+// side-effect: also replaced that what with \0 if it is found
+int ulas_last_print_is_escape(char *buf, int n) {
+	int found_escape = 0;
+	// check if last printable char is an escape char
+	unsigned int buf_len = strnlen(buf, n);
+	if (buf_len == 0) {
+		return 0;
+	}
+
+	for (int i = buf_len - 1; i >= 0; i--) {
+		if (isprint(buf[i])) {
+			found_escape = buf[i] == '\\';
+			if (found_escape) {
+				buf[i] = '\0';
+			}
+			break;
+		}
+	}
+
+	return found_escape;
+}
+
+// call fgets and concats into buf until either buf is full (fatal error)
+// or a non-escape character is *not* the last chracter of a line
+// returns number of lines read
+int ulas_fgets(char *buf, int n, FILE *src) {
+	char internal_buf[ULAS_LINEMAX+1];
+	buf[0] = '\0';
+	internal_buf[ULAS_LINEMAX] = '\0';
+
+	int lines_read = 0;
+
+	do {
+		char *res = fgets(internal_buf, ULAS_LINEMAX, src);
+
+		// bail early
+		if (res == NULL) {
+			break;
+		}
+		
+		strncat(buf, internal_buf, n);
+
+		lines_read++;
+	} while(ulas_last_print_is_escape(buf, n));
+
+	return lines_read;
+}
+
 int ulas_preprocnext(struct ulas_preproc *pp, FILE *dst, FILE *src, char *buf,
                      int n) {
   int rc = 1;
-  if (fgets(buf, n, src) != NULL) {
-    ulas.line++;
+	int lines_read = 0;
+  if ((lines_read = ulas_fgets(buf, n, src)) != 0) {
+    ulas.line += lines_read;
 
     unsigned long buflen = strlen(buf);
 
@@ -2707,7 +2757,7 @@ fail:
 
 int ulas_asmnext(FILE *dst, FILE *src, char *buf, int n) {
   int rc = 1;
-  if (fgets(buf, n, src) != NULL) {
+  if (ulas_fgets(buf, n, src) != 0) {
     unsigned long buflen = strlen(buf);
     if (ulas_asmline(dst, src, buf, buflen) == -1) {
       rc = -1;
diff --git a/tests/multiline.bin b/tests/multiline.bin
new file mode 100644
index 0000000000000000000000000000000000000000..955058a6897aaa47f707007d39245fc800bbf760
GIT binary patch
literal 17
YcmZ=@P;_|Ykdc~`lV6@+l#{{$05hTn00000

literal 0
HcmV?d00001

diff --git a/tests/multiline.s b/tests/multiline.s
new file mode 100644
index 0000000..65bbcb7
--- /dev/null
+++ b/tests/multiline.s
@@ -0,0 +1,17 @@
+#define test 123\
+456
+
+ld b\
+	, b
+nop
+ld hl, test
+
+ld b\
+\
+\
+, b
+
+.str "hello\
+world"
+
+nop
-- 
2.30.2