Commit: 04a05b78b3b72e9e218e1c621b0f695e7365dd55 - sapphire_lisp (git)

Baremetal Lisp interpreter and compiler for low-resource devices

Commit MetaInfo

• Revision: 04a05b78b3b72e9e218e1c621b0f695e7365dd55 (tree)
• Time: 2020-09-13 06:39:50
• Author: AlaskanEmily <emily@alas...>
• Commiter: AlaskanEmily

Log Message

Add pointers and protocols to the S-expression library

Change Summary

• modified: makefile
• modified: sl_s.h

Incremental Difference

--- a/makefile
+++ b/makefile
@@ -4,7 +4,7 @@
 # Unix makefile.
 
 CC=cc
-CFLAGS=-g -Wall -Wextra -pedantic -Werror -ansi -Wshadow -Wno-old-style-declaration -Wno-unknown-warning-option
+CFLAGS=-g -Wall -Wextra -pedantic -Werror -ansi -Wshadow -Wno-old-style-declaration -Wno-unknown-warning-option -DSL_S_ENABLE_POINTERS -DSL_S_ENABLE_PROTOCOLS
 COMPILEFLAG=-c
 COUT=-o 
 

--- a/sl_s.h
+++ b/sl_s.h
@@ -78,19 +78,26 @@ extern "C"{
  * If SL_S_DO_NOT_STRIP_BITS is set, then the tag bits will not be stripped
  * from the pointers on unpacking. This is useful for hardware with mirrored
  * RAM, although it is likely not useful when SL_S_TAG_LSB is set.
+ *
+ * Note that the settings for SL_S_ENABLE_PROTOCOLS and SL_S_ENABLE_POINTERS
+ * will affect the defaults as well.
  */
 /*****************************************************************************/
 
 #if !((defined SL_S_TAG_LSB) || (defined SL_S_TAG_MSB))
-#define SL_S_TAG_LSB
+# define SL_S_TAG_LSB
 #elif (defined SL_S_TAG_LSB) && (defined SL_S_TAG_MSB)
-#error Invalid configuration: both SL_S_TAG_LSB and SL_S_TAG_MSB are set.
+# error Invalid configuration: both SL_S_TAG_LSB and SL_S_TAG_MSB are set.
 #endif
 
 #ifndef SL_S_NUM_TAG_BITS
-#define SL_S_NUM_TAG_BITS 1
+# if (defined SL_S_ENABLE_PROTOCOLS) || (defined SL_D_ENABLE_POINTERS)
+#   define SL_S_NUM_TAG_BITS 2
+# else
+#  define SL_S_NUM_TAG_BITS 1
+# endif
 #elif SL_S_NUM_TAG_BITS < 1
-#error Invalid configuration: SL_S_TAG_BITS must be greater than zero.
+# error Invalid configuration: SL_S_TAG_BITS must be greater than zero.
 #endif
 
 /*****************************************************************************/
@@ -100,6 +107,15 @@ extern "C"{
 #define SL_S_LIST_TAG 0
 #define SL_S_ATOM_TAG 1
 
+#ifdef SL_S_ENABLE_PROTOCOLS
+# define SL_S_PROTOCOL_TAG 2
+# define SL_S_PROTO_TAG SL_S_PROTOCOL_TAG
+#endif
+
+#ifdef SL_S_ENABLE_POINTERS
+# define SL_S_POINTER_TAG 3
+#endif
+
 #define SL_S_PTR_BITS (sizeof(void*)<<3)
 
 #ifdef SL_S_TAG_LSB
@@ -150,11 +166,37 @@ extern "C"{
 #define SL_S_IS_LIST(X) (SL_S_PTR_TAG((X), SL_S_NUM_TAG_BITS) == SL_S_LIST_TAG)
 #define SL_S_IS_ATOM(X) (SL_S_PTR_TAG((X), SL_S_NUM_TAG_BITS) == SL_S_ATOM_TAG)
 
+#ifdef SL_S_ENABLE_PROTOCOLS
+# define SL_S_IS_PROTOCOL(X) \
+    (SL_S_PTR_TAG((X), SL_S_NUM_TAG_BITS) == SL_S_PROTOCOL_TAG)
+# define SL_S_IS_PROTO SL_S_IS_PROTOCOL
+#endif
+
+#ifdef SL_S_ENABLE_POINTERS
+# define SL_S_IS_POINTER(X) \
+    (SL_S_PTR_TAG((X), SL_S_NUM_TAG_BITS) == SL_S_POINTER_TAG)
+# define SL_S_IS_PTR SL_S_IS_POINTER
+#endif
+
 #define SL_S_MK_LIST(X) SL_S_TAG_PTR((X), SL_S_LIST_TAG)
 #define SL_S_MK_ATOM(X) (SL_S_IS_NIL((X)) ? \
     SL_S_NIL : \
     SL_S_TAG_PTR((X), SL_S_ATOM_TAG))
 
+#ifdef SL_S_ENABLE_PROTOCOLS
+# define SL_S_MK_PROTOCOL(X) (SL_S_IS_NIL(X) ? \
+    SL_S_NIL : \
+    SL_S_TAG_PTR((X), SL_S_PROTOCOL_TAG))
+# define SL_S_MK_PROTO SL_S_MK_PROTOCOL
+#endif
+
+#ifdef SL_S_ENABLE_POINTERS
+# define SL_S_MK_POINTER(X) (SL_S_IS_NIL(X) ? \
+    SL_S_NIL : \
+    SL_S_TAG_PTR((X), SL_S_POINTER_TAG))
+# define SL_S_MK_PTR SL_S_MK_POINTER
+#endif
+
 /*****************************************************************************/
 /* Len/Refcount typedefs */
 
@@ -261,6 +303,51 @@ struct SL_S_List{
 };
 
 /*****************************************************************************/
+
+#ifdef SL_S_ENABLE_PROTOCOLS
+
+/*****************************************************************************/
+/** Represents an protocol object. */
+struct SL_S_Protocol{
+    sl_s_ref_t ref;
+#ifndef SL_S_NO_PARSER_INFO
+    sl_s_len_t line;
+#endif
+    SL_S_FUNC_PTR(void, destroy)(struct SL_S_Protocol *that);
+};
+
+/*****************************************************************************/
+
+#endif
+
+/*****************************************************************************/
+
+#ifdef SL_S_ENABLE_POINTERS
+
+/*****************************************************************************/
+/** Holds a boxed pointer.
+ *
+ * Sadly, for use in Sapphire Lisp, all pointers must be boxed to work properly
+ * with tag bits.
+ *
+ * NULL (in C) can still be represented as an unboxed NIL, and SL_S_MK_PTR will
+ * actually cause this to happen when possible.
+ *
+ * The ref-count only applies to the pointer's box.
+ */
+struct SL_S_Pointer{
+    sl_s_ref_t ref;
+#ifndef SL_S_NO_PARSER_INFO
+    sl_s_len_t line;
+#endif
+    void *data;
+};
+
+/*****************************************************************************/
+
+#endif
+
+/*****************************************************************************/
 /** Shared struct to allow access to refcount without conditional casts */
 struct SL_S_Ref{
     sl_s_ref_t ref;