misc/kforth: Restart the world.

Makefile

@@ -1,23 +1,28 @@
-CXXSTD :=	c++14
-CXXFLAGS :=	-std=$(CXXSTD) -Wall -Werror -O0 -g
+PLATFORM ?=	default
+CSTD :=		c99
+CFLAGS ?=	-std=$(CSTD) -Wall -Werror -O0 -g -DPLATFORM_$(PLATFORM)
 LDFLAGS :=	-static
-OBJS :=		linux/io.o	\
-		io.o		\
-		system.o	\
-		parser.o	\
+OBJS :=		stack.o		\
+		eval.o		\
 		word.o		\
-		dict.o		\
-		kforth.o
-TARGET :=	kforth
+		kf.o
+TARGET :=	kf-$(PLATFORM)
 
 all: $(TARGET)
 
 $(TARGET): $(OBJS)
-	$(CXX) $(LDFLAGS) -o $@ $(OBJS)
+	$(CC) $(LDFLAGS) -o $@ $(OBJS)
 
-clean:
-	rm -f $(OBJS) $(TARGET)
+clean-objs:
+	rm -f $(OBJS)
+
+clean: clean-objs
+	rm -f kf-pc kf-default
 
 install: $(TARGET)
 	cp $(TARGET) ~/bin
 	chmod 0755 ~/bin/$(TARGET)
+
+cross:
+	make PLATFORM=default clean-objs all
+	make PLATFORM=pc clean-objs all

default/defs.h

@@ -1,14 +1,12 @@
-#ifndef __KF_PLATFORM_DEFAULT_H__
-#define __KF_PLATFORM_DEFAULT_H__
-
-#include <stdint.h>
+#ifndef __KF_DEFAULT_DEFS_H__
+#define __KF_DEFAULT_DEFS_H__
 
 typedef int	KF_INT;
 typedef uintptr_t KF_ADDR;
 
-constexpr static size_t STACK_SIZE = 48 / sizeof(KF_INT);
-constexpr static size_t	DICT_SIZE  = 4096;
-constexpr static size_t	ARENA_SIZE = 256;
+static const size_t	DSTACK_SIZE = 12;
+static const size_t	RSTACK_SIZE = 12;
+static const size_t	DICT_SIZE = 4096;
 
+#endif /* __KF_DEFAULT_DEFS_H__ */
 
-#endif // __KF_PLATFORM_DEFAULT_H__

defs.h

@@ -1,12 +1,15 @@
 #ifndef __KF_DEFS_H__
 #define __KF_DEFS_H__
 
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
 
-#if PLATFORM == PC
+#ifdef PLATFORM_pc
 #include "pc/defs.h"
 #else
 #include "default/defs.h"
 #endif
 
 
-#endif __KF_DEFS_H__
+#endif /* __KF_DEFS_H__ */

doc/part-0x08.rst

@@ -16,3 +16,17 @@ Some design choices that didn't really work out:
 + my linked list approach to the dictionary
 + my class-based approach to words
 
+I get the distinct feeling that I could (maybe should) be doing this in C99, so
+I think I'll switch to that.
+
+The new design
+^^^^^^^^^^^^^^
+
+I'll need to provide a few initial pieces:
+
+1. eval.c
+2. stack.c
+3. the platform parts
+
+I'll skip the parser at first and hand hack some things, then try to
+port over my I/O layer from before.

eval.c

@@ -0,0 +1,21 @@
+#include "defs.h"
+#include "eval.h"
+
+#include <string.h>
+
+void
+cwexec(uintptr_t entry)
+{
+	uintptr_t	target = 0;
+	uintptr_t	codeword = 0;
+
+	memcpy(&codeword, (void *)entry, sizeof(uintptr_t));	
+	memcpy(&target, (void *)(entry + sizeof(uintptr_t)), sizeof(uintptr_t));	
+	((void(*)(uintptr_t))codeword)(target);
+}
+
+void
+nexec(uintptr_t target)
+{
+	((void(*)(void))target)();
+}

eval.h

@@ -0,0 +1,28 @@
+#ifndef __KF_EVAL_H__
+#define __KF_EVAL_H__
+
+#include "defs.h"
+
+
+/*
+ * cwexec is the codeword executor. It assumes that the uintptr_t
+ * passed into it points to the correct executor (e.g. nexec), 
+ * which is called with the next address.
+ */
+void	cwexec(uintptr_t);
+
+
+/*
+ * nexec is the native executor. 
+ *
+ * It should take a uintptr_t containing the address of a code block
+ * and will execute the function starting there. The function should
+ * half the signature void(*target)(void) - a function returning
+ * nothing and taking no arguments.
+ */
+void	nexec(uintptr_t);
+
+static const uintptr_t	nexec_p = (uintptr_t)&nexec;
+
+
+#endif /* __KF_EVAL_H__ */

kf.c

@@ -0,0 +1,28 @@
+#include "defs.h"
+#include "eval.h"
+#include "stack.h"
+#include "word.h"
+
+#include <stdio.h>
+#include <string.h>
+
+void
+hello(void)
+{
+	printf("hello, world\n");
+}
+
+int
+main(void)
+{
+	dstack_push(2);
+	dstack_push(3);
+
+	uint8_t	arena[128] = {0};
+	uintptr_t arena_p = (uintptr_t)arena;
+	store_native(arena, hello);
+
+	cwexec(arena_p);
+
+	printf("finished\n");
+}

pc/defs.h

@@ -1,14 +1,11 @@
-#ifndef __KF_PLATFORM_PC_H__
-#define __KF_PLATFORM_PC_H__
-
-#include <stdint.h>
+#ifndef __KF_PC_DEFS_H__
+#define __KF_PC_DEFS_H__
 
 typedef int32_t	KF_INT;
 typedef uintptr_t KF_ADDR;
 
-constexpr static size_t STACK_SIZE = 65535;
-constexpr static size_t	DICT_SIZE  = 65535;
-constexpr static size_t	ARENA_SIZE = 65535;
+static const size_t	DSTACK_SIZE = 65535;
+static const size_t	RSTACK_SIZE = 65535;
+static const size_t	DICT_SIZE   = 65535;
 
-
-#endif // __KF_PLATFORM_PC_H__
+#endif /* __KF_PC_DEFS_H__ */

stack.c

@@ -0,0 +1,98 @@
+#include "defs.h"
+#include "stack.h"
+
+static KF_INT	dstack[DSTACK_SIZE] = {0};
+static size_t	dstack_len = 0;
+
+bool
+dstack_pop(KF_INT *a)
+{
+	if (dstack_len == 0) {
+		return false;
+	}
+
+	*a = dstack[--dstack_len];
+	return true;
+}
+
+bool
+dstack_push(KF_INT a)
+{
+	if (dstack_len == DSTACK_SIZE) {
+		return false;
+	}
+
+	dstack[dstack_len++] = a;
+	return true;
+}
+
+bool
+dstack_get(size_t i, KF_INT *a)
+{
+	if (i >= dstack_len) {
+		return false;
+	}
+
+	*a = dstack[dstack_len - i - 1];
+	return true;
+}
+
+size_t
+dstack_size()
+{
+	return dstack_len;
+}
+
+void
+dstack_clear()
+{
+	dstack_len = 0;
+}
+
+static KF_ADDR	rstack[RSTACK_SIZE] = {0};
+static size_t	rstack_len = 0;
+
+bool
+rstack_pop(KF_ADDR *a)
+{
+	if (rstack_len == 0) {
+		return false;
+	}
+
+	*a = rstack[--rstack_len];
+	return true;
+}
+
+bool
+rstack_push(KF_ADDR a)
+{
+	if (rstack_len == DSTACK_SIZE) {
+		return false;
+	}
+
+	rstack[rstack_len++] = a;
+	return true;
+}
+
+bool
+rstack_get(size_t i, KF_ADDR *a)
+{
+	if (i >= rstack_len) {
+		return false;
+	}
+
+	*a = rstack[rstack_len - i - 1];
+	return true;
+}
+
+size_t
+rstack_size()
+{
+	return rstack_len;
+}
+
+void
+rstack_clear()
+{
+	rstack_len = 0;
+}

stack.h

@@ -1,9 +1,18 @@
 #ifndef __KF_STACK_H__
 #define __KF_STACK_H__
 
+/* data stack interaction */
+bool	dstack_pop(KF_INT *);
+bool	dstack_push(KF_INT);
+bool	dstack_get(size_t, KF_INT *);
+size_t	dstack_size(void);
+void	dstack_clear(void);
 
+/* return stack interaction */
+bool	rstack_pop(KF_ADDR *);
+bool	rstack_push(KF_ADDR);
+bool	rstack_get(size_t, KF_ADDR *);
+size_t	rstack_size(void);
+void	rstack_clear(void);
 
-static
-
-
-#endif // __KF_STACK_H__
+#endif /* __KF_STACK_H__ */

word.c

@@ -0,0 +1,82 @@
+#include "defs.h"
+#include "eval.h"
+#include "word.h"
+
+#include <string.h>
+
+static uint8_t	dict[DICT_SIZE] = {0};
+static size_t	last = 0;
+
+void
+append_word(const char *name, const uint8_t len, void(*target)(void))
+{
+	store_native(dict+last, name, len, target);
+}
+
+bool
+execute(const char *name, const uint8_t len)
+{
+	size_t	offset = 0;
+	size_t	body = 0;
+	while (true) {
+		if (!match_word(dict+offset, name, len)) {
+			if ((offset = word_link(dict+offset)) == 0) {
+				return false;
+			}
+			continue;
+		}
+
+		body = word_body(dict+offset);
+		cwexec(dict + body + offset);
+		return true;
+	}
+}
+
+void
+store_native(uint8_t *entry, const char *name, const uint8_t len, void(*target)(void))
+{
+	uintptr_t	target_p = (uintptr_t)target;
+	size_t		link = 2 + len + (2 * sizeof(uintptr_t));
+
+	/* write the header */
+	entry[0] = len;
+	entry[1] = 0; // flags aren't used yet
+	memcpy(entry+2, name, len);
+	memcpy(entry+2+len, &link, sizeof(link));
+
+	/* write the native executor codeword and the function pointer */
+	memcpy(entry, (uint8_t *)(&nexec_p), sizeof(uintptr_t));
+	memcpy(entry + sizeof(uintptr_t), (uint8_t *)(&target_p), sizeof(uintptr_t));
+}
+
+bool
+match_word(uint8_t *entry, const char *name, const uint8_t len)
+{
+	if (entry[0] != len) {
+		return false;
+	}
+
+	if (memcmp(entry+2, name, len) != 0) {
+		return false;
+	}
+
+	return true;
+}
+
+size_t
+word_link(uint8_t *entry)
+{
+	size_t	link;
+
+	if (entry[0] == 0) {
+		return 0;
+	}
+	memcpy(&link, entry+2+entry[0], sizeof(link));
+	return link;
+}
+
+size_t
+word_body(uint8_t *entry)
+{
+	return 2 + entry[0] + sizeof(size_t);
+}

word.h

@@ -0,0 +1,42 @@
+#ifndef __KF_WORD_H__
+#define __KF_WORD_H__
+
+/*
+ * Every word in the dictionary starts with a header:
+ * uint8_t	 length;
+ * uint8_t	 flags;
+ * char		*name;
+ * uintptr_t	 next;
+ *
+ * The body looks like the following:
+ * uintptr_t	 codeword;
+ * uintptr_t	 body[];
+ *
+ * The codeword is the interpreter for the body. This is defined in
+ * eval.c. Note that a native (or builtin function) has only a single
+ * body element.
+ *
+ * The body of a native word points to a function that's compiled in already.
+ */
+
+
+/*
+ * store_native writes a new dictionary entry for a native-compiled
+ * function.
+ */
+void	store_native(uint8_t *, const char *, const uint8_t, void(*)(void));
+
+/*
+ * match_word returns true if the current dictionary entry matches the
+ * token being searched for.
+ */
+bool	match_word(uint8_t *, const char *, const uint8_t);
+
+/*
+ * word_link returns the offset to the next word.
+ */
+size_t	word_link(uint8_t *);
+	
+size_t	word_body(uint8_t *);
+
+#endif /* __KF_WORD_H__ */