misc/kforth: Fix a bunch of bugs from part 0x08.

doc/part-0x08.rst

@@ -1,7 +1,7 @@
 Write You a Forth, 0x08
 -----------------------
 
-:date: 2018-03-01 19:31
+:date: 2018-03-05 21:42
 :tags: wyaf, forth
 
 After reading some more in Threaded Interpreted Languages (TIL_ from now on),
@@ -199,7 +199,7 @@ Reading TIL has given me some new ideas on how to implement words::
         #endif /* __KF_WORD_H__ */
 
 The codeword is the big changer here. I've put a native evaluator and
-a codeword executor in the ``eval`` files:
+a codeword executor in the ``eval`` files::
 
         #ifndef __KF_EVAL_H__
         #define __KF_EVAL_H__
@@ -238,6 +238,8 @@ The implementations of these are short::
 
 ``nexec`` just casts its target to a void function and calls it.
 
+::
+
         void
         nexec(uintptr_t target)
         {
@@ -248,6 +250,8 @@ The implementations of these are short::
 is the executor, and the next is the start of the code body. In the
 case of native execution, this is a pointer to a function.
 
+::
+
         void
         cwexec(uintptr_t entry)
         {
@@ -317,7 +321,7 @@ adds a new word to the dictionary, and the second attempts to look
 up a word by name and execute it::
 
         void
-        append_word(const char *name, const uint8_t len, void(*target)(void))
+        append_native_word(const char *name, const uint8_t len, void(*target)(void))
         {
         	store_native(dict+last, name, len, target);
         }
@@ -341,6 +345,41 @@ up a word by name and execute it::
         	}
         }
 
+Actually, now that I think about it, maybe I should also add in a function
+to return a uintptr_t to the word, too. Should this point to the header or
+to the body? My first instinct is to point to the header and have the caller
+(me) use ``word_body`` to get the actual body. That being said, however,
+we already have the useful information from the header (namely, the name and
+length); the link is only useful for the search phase. Following this logic
+means that ``lookup`` will return a pointer to the body. So say we all::
+        
+        bool
+        lookup(const char *name, const uint8_t len, uintptr_t *ptr)
+        {
+        	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);
+        		*ptr = (uintptr_t)(dict + offset + body);
+        		return true;
+        	}
+        
+        }
+
+The rest of the functions in the header (all of which are publicly
+visible) are made available for use later. Maybe (but let's be honest,
+probably not) I'll go back later and make these functions private.
+
+The first such function stores a native (built-in) word. This is what
+``append_native_word`` is built around::
+
         void
         store_native(uint8_t *entry, const char *name, const uint8_t len, void(*target)(void))
         {
@@ -358,6 +397,9 @@ up a word by name and execute it::
         	memcpy(entry + sizeof(uintptr_t), (uint8_t *)(&target_p), sizeof(uintptr_t));
         }
         
+The rest of the functions are utility functions. ``match_word`` is used
+to... match words::
+
         bool
         match_word(uint8_t *entry, const char *name, const uint8_t len)
         {
@@ -372,6 +414,10 @@ up a word by name and execute it::
         	return true;
         }
 
+Finally, ``word_link`` returns the offset to the next function (e.g. so
+as to be able to do ``entry+offset``) and ``word_body`` returns the offset
+to the body of the word::
+        
         size_t
         word_link(uint8_t *entry)
         {
@@ -390,3 +436,6 @@ up a word by name and execute it::
         	return 2 + entry[0] + sizeof(size_t);
         }
         
+
+That about wraps up this chunk of work. Next to maybe start porting builtins? I
+also need to rewrite the parser and I/O layer.

kf.c

@@ -4,6 +4,7 @@
 #include "word.h"
 
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 
 void
@@ -18,11 +19,18 @@ main(void)
 	dstack_push(2);
 	dstack_push(3);
 
-	uint8_t	arena[128] = {0};
+	append_native_word("hello", 5, hello);
-	uintptr_t arena_p = (uintptr_t)arena;
+	uintptr_t	hwb = 0;
-	store_native(arena, "hello", 5, hello);
 
-	cwexec(arena_p);
+	if (!lookup("hello", 5, &hwb)) {
+		fprintf(stderr, "failed to lookup 'hello'\n");
+		exit(1);
+	}
+	printf("hello: 0x%lx\n", (unsigned long)hwb);
+	if (!execute("hello", 5)) {
+		fprintf(stderr, "failed to execute 'hello'\n");
+		exit(1);
+	}
 
 	printf("finished\n");
 }

word.c

@@ -8,7 +8,7 @@ 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))
+append_native_word(const char *name, const uint8_t len, void(*target)(void))
 {
 	store_native(dict+last, name, len, target);
 }
@@ -32,11 +32,32 @@ execute(const char *name, const uint8_t len)
 	}
 }
 
+bool
+lookup(const char *name, const uint8_t len, uintptr_t *ptr)
+{
+	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);
+		*ptr = (uintptr_t)(dict + offset + body);
+		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));
+	size_t		offset = 2 + len + sizeof(size_t);
+	size_t		link = offset + (2 * sizeof(uintptr_t));
 
 	/* write the header */
 	entry[0] = len;
@@ -45,8 +66,9 @@ store_native(uint8_t *entry, const char *name, const uint8_t len, void(*target)(
 	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+offset, (uint8_t *)(&nexec_p), sizeof(uintptr_t));
-	memcpy(entry + sizeof(uintptr_t), (uint8_t *)(&target_p), sizeof(uintptr_t));
+	offset += sizeof(uintptr_t);
+	memcpy(entry+offset, (uint8_t *)(&target_p), sizeof(uintptr_t));
 }
 
 bool

word.h

@@ -19,6 +19,9 @@
  * The body of a native word points to a function that's compiled in already.
  */
 
+void	append_native_word(const char *, const uint8_t, void(*)(void));
+bool	execute(const char *, const uint8_t);
+bool	lookup(const char *, const uint8_t, uintptr_t *);
 
 /*
  * store_native writes a new dictionary entry for a native-compiled