Day 1. Assembly code is being generated, on a monkey see, monkey do basis;

but it doesn't link because of a missing library; and having moved source
files around the Makefile currently doesn't work.

.gitignore

@@ -57,3 +57,6 @@ dkms.conf
 .project
 .settings/
 build/
+
+# Munit
+src/munit.*

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "munit"]
+	path = munit
+	url = https://github.com/nemequ/munit.git

Makefile

@@ -15,7 +15,7 @@ else
     $(error Build mode $(BUILD_MODE) not supported by this Makefile)
 endif
 
-SRC_DIR=$(PROJECT_ROOT)/src
+SRC_DIR=$(PROJECT_ROOT)/src/c
 
 all:	grendel
 

README.md

@@ -36,11 +36,11 @@ Tags will be allocated as follows:
 
 | 3-bit value | 7-bit value | (Hex) | Interpretation                                               |
 | ----------- | ----------- | ----- | ------------------------------------------------------------ |
-| 0           | 0           | 0x0   | a pointer; an offset into the vector of words.               |
+| 0           | 0           | 0x0   | an error object, whose payload is a 3 character error code.  |
-| 1           | 1           | 0x1   | a signed 28 bit integer.                                     |
+| 1           | 1           | 0x1   | a pointer; an offset into the vector of words.               |
-| 2           | 2           | 0x2   | a character; possibly just a byte, or possibly a 16 bit wchar. |
+| 2           | 2           | 0x2   | a signed 28 bit integer.                                     |
-| 3           | 3           | 0x3   | unassigned (possibly a floating point number, later.)        |
+| 3           | 3           | 0x3   | a character; possibly just a byte, or possibly a 16 bit wchar. |
-| 4           | 4           | 0x4   | unassigned                                                   |
+| 4           | 4           | 0x4   | unassigned (possibly a floating point number, later.)        |
 | 5           | 5           | 0x5   | unassigned                                                   |
 | 6           | 6           | 0x6   | unassigned                                                   |
 | 7           | 7           | 0x7   | a cons cell                                                  |

munit

@@ -0,0 +1 @@
+Subproject commit fbbdf1467eb0d04a6ee465def2e529e4c87f2118

src/c/day1.c

@@ -0,0 +1,26 @@
+/**
+ *  day1.c
+ *
+ *  Grendel: a compiling Beowulf reimplementation.
+ *
+ *  Day 1 of work towards a compiler... eventually..
+ *
+ *  This is a straight copy of Noah Zentzis' work. There's no original work of
+ *  mine here, yet
+ *
+ *  (c) 2026 Simon Brooke <simon@journeyman.cc>
+ *  Licensed under GPL version 2.0, or, at your option, any later version.
+ */
+
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h>
+
+__attribute__((__cdecl__))
+extern int lisp_entry();
+
+int main(int argc, const char **argv) {
+    int val = lisp_entry();
+    printf("%d\n", val);
+    return 0;
+}

src/c/error.c

@@ -0,0 +1,29 @@
+/**
+ *  error.c
+ *
+ *  Grendel: a compiling Beowulf reimplementation.
+ *
+ *  The error handling subsystem.
+ *
+ *  Error codes are detailed in section 6.3, page 32, of the
+ *  Lisp 1.5 Programmer's Manual. I shall in so far as possible follow
+ *  those codes.
+ *
+ *  (c) 2026 Simon Brooke <simon@journeyman.cc>
+ *  Licensed under GPL version 2.0, or, at your option, any later version.
+ */
+
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h>
+
+#include "error.h"
+#include "memory.h"
+
+uint32_t make_error( char* code) {
+	uint32_t error = 0;
+
+	strncpy( (char *)((&error) &1), code, 3);
+
+	return error;
+}

src/c/error.h

@@ -0,0 +1,45 @@
+/**
+ *  error.h
+ *
+ *  Grendel: a compiling Beowulf reimplementation.
+ *
+ *  The error handling subsystem.
+ *
+ *  Error codes are detailed in section 6.3, page 32, of the
+ *  Lisp 1.5 Programmer's Manual. I shall in so far as possible follow
+ *  those codes.
+ *
+ *  (c) 2026 Simon Brooke <simon@journeyman.cc>
+ *  Licensed under GPL version 2.0, or, at your option, any later version.
+ */
+
+#ifndef __grendel_error_h
+#define __grendel_error_h
+
+#include <stdint.h>
+
+uint32_t make_error( char* code);
+
+/**
+ * @brief error codes
+ *
+ *  Error codes are detailed in section 6.3, page 32, of the
+ *  Lisp 1.5 Programmer's Manual. I shall in so far as possible follow
+ *  those codes.
+ *
+ *  Error codes comprise a one or two alphabetic character category, followed
+ *  by a single digit number. A space is shown in the manual between the
+ *  category and the number, but I have not followed that here for reasons.
+ */
+
+#define APPLIED_FUNCTION_CALLED_ERROR 	(make_error( "A1"))
+#define UNDEFINED_FUNCTION_APPLY_ERROR	(make_error( "A2"))
+#define COND_UNSATISFIED_ERROR			(make_error( "A3"))
+#define SETQ_ON_NONEXISTANT_VAR_ERROR	(make_error( "A4"))
+#define SET_ON_NONEXISTANT_VAR_ERROR	(make_error( "A5"))
+#define NO_TARGET_FOR_GO_ERROR			(make_error( "A6"))
+#define TOO_MANY_ARGUMENTS_ERROR		(make_error( "A7"))
+#define UNBOUND_VARIABLE_ERROR			(make_error( "A8"))
+#define UNDEFINED_FUNCTION_EVAL_ERROR	(make_error( "A9"))
+
+#endif

src/c/grendel.c

@@ -15,6 +15,11 @@
 #include <stdint.h>
 
 #include "memory.h"
+#include "version.h"
+
+__attribute__((__cdecl__))
+extern int lisp_entry();
+
 
 void showbits( unsigned int x )
 {
@@ -28,18 +33,12 @@ void showbits( unsigned int x )
 
 int main(int argc, char **argv) {
 
-	printf( "Grendel:\n");
+	printf( "Grendel, a compiler for Beowulf: version %s\n", VERSION);
-	int i;
-
-	for ( i = 0; i < 8; i++) {
-		printf( "\ti = %d (%b, 0x%x);\n", i, i, i);
-	}
-	for ( ; i < 128; i++) {
-		if ((i & TAG32MASK) == TAG32MASK) {
-			printf( "\ti = %d (%b, 0x%x);\n", i, i, i);
-		}
-	}
 
+    int val = lisp_entry();
+    printf("%d\n", val);
+    return 0;
+}
 
 	return 0;
 }

src/c/lisp.c

@@ -0,0 +1,19 @@
+/**
+ *  lisp.c
+ *
+ *  Grendel: a compiling Beowulf reimplementation.
+ *
+ *  The compiler... eventually..
+ *
+ *  Error codes are detailed in section 6.3, page 32, of the
+ *  Lisp 1.5 Programmer's Manual. I shall in so far as possible follow
+ *  those codes.
+ *
+ *  (c) 2026 Simon Brooke <simon@journeyman.cc>
+ *  Licensed under GPL version 2.0, or, at your option, any later version.
+ */
+
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h>
+

src/c/memory.h

@@ -16,28 +16,28 @@
 
 /* Tags for 32 bit objects, with 3 bits of tag an one mark bit */
 
+#define ERRORTV		(0)
 /**
  * @brief This pointer object is an actual pointer -- an offset into consspace.
  */
-#define OFFSETTV 		(0)
+#define OFFSETTV 	(1)
 /**
  * @brief This pointer object is actually a 28 bit integer value.
  */
-#define INTEGERTV 		(1)
+#define INTEGERTV 	(2)
 /**
  * @brief A character; initially just a byte. but potentially a 16 bit wchar.
  */
- #define CHARTV         (2)
+ #define CHARTV		(3)
 /**
  * @brief A 16 bit floating point number.  (future expansion)
  * 
  * Yes, it could be 28 bit, but I think that would hurt my brain. 
  */
-#define FLOATTV         (3) 
+#define FLOATTV		(4)
 
 /*
- * Values 4..6 inclusive reserved further data types, including maybe
+ * Values 5 and 6 are available for further 32 bit data types.
- * implementing reals later.
  */
 
 /**
@@ -87,12 +87,12 @@
 
 #define FREETV 		(0x7f)
 
-#define MARKMASK 	((unsigned int)1)
+#define MARKMASK 	((uint64_t)1)
-#define TAG32MASK 	((unsigned int)7)
+#define TAG32MASK 	((uint64_t)7)
-#define TAG64MASK 	((unsigned int)0xf)
+#define TAG64MASK 	((uint64_t)0xf)
 
-#define MASK64 (0xffffffffffffffff)
+#define MASK64 ((uint64_t)0xffffffffffffffff)
-#define MASK32 (0xffffffff)
+#define MASK32 ((uint64_t)0xffffffff)
 
 /**
  * @brief Return the mark bit of this object.

src/c/version.h

@@ -0,0 +1,15 @@
+/**
+ *  version.h
+ *
+ *  Grendel: a compiling Beowulf reimplementation.
+ *
+ *  (c) 2026 Simon Brooke <simon@journeyman.cc>
+ *  Licensed under GPL version 2.0, or, at your option, any later version.
+ */
+
+#ifndef __grendel_version_h
+#define __grendel_version_h
+
+#define VERSIOM "Aelfhere"
+
+#ifndef

src/guile/day1.scm

@@ -0,0 +1,30 @@
+(define emit (lambda args (apply simple-format #t args)
+                          (newline)))
+
+(define (compile-program program)
+  (emit ".text")
+  (emit ".p2align 4,,15")
+  (emit ".globl lisp_entry")
+  (emit "lisp_entry:")
+
+  ; handle incoming call from C
+  (emit "push %esi")
+  (emit "push %edi")
+  (emit "push %edx")
+
+  ; our code goes here
+  (emit "movl $42, %eax")
+
+  ; restore state for return to C
+  (emit "pop %edx")
+  (emit "pop %edi")
+  (emit "pop %esi")
+  (emit "ret"))
+
+(define (compile-to-binary program)
+  (begin
+    (with-output-to-file "/tmp/compiled.s"
+      (lambda () (compile-program program)))
+    (system "gcc -fomit-frame-pointer -m32 /tmp/compiled.s src/c/day1.c")))
+
+