WIP

include/asm/rpn.h

@@ -17,52 +17,29 @@
 #define MAXRPNLEN 1048576
 
 struct Expression {
-	int32_t  val;           // If the expression's value is known, it's here
-	char     *reason;       // Why the expression is not known, if it isn't
-	bool     isKnown;       // Whether the expression's value is known
-	bool     isSymbol;      // Whether the expression represents a symbol
-	uint8_t  *rpn;          // Array of bytes serializing the RPN expression
-	uint32_t rpnCapacity;   // Size of the `tRPN` buffer
-	uint32_t rpnLength;     // Used size of the `tRPN` buffer
-	uint32_t rpnPatchSize;  // Size the expression will take in the obj file
+	size_t   rpnLength;     // Used size of the `rpn` buffer
+	uint32_t rpnPatchSize;  // Size the expression will take in the object file
+	uint8_t  rpn[];         // Array of bytes serializing the RPN expression
 };
 
-/*
- * Determines if an expression is known at assembly time
- */
-static inline bool rpn_isKnown(const struct Expression *expr)
-{
-	return expr->isKnown;
-}
-
-/*
- * Determines if an expression is a symbol suitable for const diffing
- */
-static inline bool rpn_isSymbol(const struct Expression *expr)
-{
-	return expr->isSymbol;
-}
-
-void rpn_Symbol(struct Expression *expr, char const *symName);
-void rpn_Number(struct Expression *expr, uint32_t i);
-void rpn_LOGNOT(struct Expression *expr, const struct Expression *src);
-struct Symbol const *rpn_SymbolOf(struct Expression const *expr);
-bool rpn_IsDiffConstant(struct Expression const *src, struct Symbol const *symName);
-void rpn_BinaryOp(enum RPNCommand op, struct Expression *expr,
-		  const struct Expression *src1,
-		  const struct Expression *src2);
-void rpn_HIGH(struct Expression *expr, const struct Expression *src);
-void rpn_LOW(struct Expression *expr, const struct Expression *src);
-void rpn_ISCONST(struct Expression *expr, const struct Expression *src);
-void rpn_UNNEG(struct Expression *expr, const struct Expression *src);
-void rpn_UNNOT(struct Expression *expr, const struct Expression *src);
-void rpn_BankSymbol(struct Expression *expr, char const *symName);
-void rpn_BankSection(struct Expression *expr, char const *sectionName);
-void rpn_BankSelf(struct Expression *expr);
-void rpn_SizeOfSection(struct Expression *expr, char const *sectionName);
-void rpn_StartOfSection(struct Expression *expr, char const *sectionName);
-void rpn_Free(struct Expression *expr);
-void rpn_CheckHRAM(struct Expression *expr, const struct Expression *src);
-void rpn_CheckRST(struct Expression *expr, const struct Expression *src);
+// Terminals (literals)
+struct Expression *rpn_BankSymbol(char const *symName);
+struct Expression *rpn_BankSection(char const *sectionName);
+struct Expression *rpn_BankSelf(void);
+struct Expression *rpn_SizeOfSection(char const *sectionName);
+struct Expression *rpn_StartOfSection(char const *sectionName);
+struct Expression *rpn_Number(uint32_t i);
+struct Expression *rpn_Symbol(char const *symName);
+// Unary operators
+struct Expression *rpn_HIGH(struct Expression *expr); // Thin wrapper, never emitted in object files
+struct Expression *rpn_LOW(struct Expression *expr); // Thin wrapper, never emitted in object files
+struct Expression *rpn_ISCONST(struct Expression *expr); // Never emitted in object files, constant
+struct Expression *rpn_NEG(struct Expression *expr);
+struct Expression *rpn_NOT(struct Expression *expr);
+struct Expression *rpn_LOGNOT(struct Expression *expr);
+struct Expression *rpn_CheckHRAM(struct Expression *expr);
+struct Expression *rpn_CheckRST(struct Expression *expr);
+// Binary operators
+struct Expression *rpn_BinaryOp(struct Expression *lhs, enum RPNCommand op, struct Expression *rhs);
 
 #endif /* RGBDS_ASM_RPN_H */

include/helpers.h

@@ -9,6 +9,10 @@
 #ifndef HELPERS_H
 #define HELPERS_H
 
+#include <stdint.h>
+
+#include "platform.h"
+
 // Of course, MSVC does not support C11, so no _Noreturn there...
 #ifdef _MSC_VER
 	#define _Noreturn __declspec(noreturn)
@@ -88,4 +92,19 @@
 #define STR(x) #x
 #define EXPAND_AND_STR(x) STR(x)
 
+// Helper function to write a LE 32-bit value to a buffer
+
+static inline uint32_t readLE32(uint8_t ptr[MIN_NB_ELMS(4)])
+{
+	return ptr[0] | ptr[1] << 8 | ptr[2] << 16 | ptr[3] << 24;
+}
+
+static inline void writeLE32(uint8_t ptr[MIN_NB_ELMS(4)], uint32_t i)
+{
+	ptr[0] = i;
+	ptr[1] = i >> 8;
+	ptr[2] = i >> 16;
+	ptr[3] = i >> 24;
+}
+
 #endif /* HELPERS_H */

include/linkdefs.h

@@ -28,17 +28,17 @@ enum RPNCommand {
 	RPN_MUL			= 0x02,
 	RPN_DIV			= 0x03,
 	RPN_MOD			= 0x04,
-	RPN_UNSUB		= 0x05,
+	RPN_UNSUB		= 0x05, // FIXME: should be renamed to "NEG" for consistency
 	RPN_EXP			= 0x06,
 
 	RPN_OR			= 0x10,
 	RPN_AND			= 0x11,
 	RPN_XOR			= 0x12,
-	RPN_UNNOT		= 0x13,
+	RPN_UNNOT		= 0x13, // FIXME: should be renamed to "NOT" for consistency
 
 	RPN_LOGAND		= 0x21,
 	RPN_LOGOR		= 0x22,
-	RPN_LOGUNNOT		= 0x23,
+	RPN_LOGUNNOT		= 0x23, // FIXME: should be renamed to "LOGNOT" for consistency
 
 	RPN_LOGEQ		= 0x30,
 	RPN_LOGNE		= 0x31,
@@ -49,6 +49,7 @@ enum RPNCommand {
 
 	RPN_SHL			= 0x40,
 	RPN_SHR			= 0x41,
+	RPN_ISCONST             = 0x42, // This is supposed to stay internal to RGBASM
 
 	RPN_BANK_SYM		= 0x50,
 	RPN_BANK_SECT		= 0x51,

src/asm/parser.y

@@ -442,7 +442,7 @@ enum {
 {
 	char symName[MAXSYMLEN + 1];
 	char string[MAXSTRLEN + 1];
-	struct Expression expr;
+	struct Expression *expr;
 	int32_t constValue;
 	enum SectionModifier sectMod;
 	struct SectionSpec sectSpec;

src/asm/rgbasm.5

@@ -168,12 +168,13 @@ equivalent to multiplying and dividing by 2 to the power of b, respectively.
 .Pp
 Comparison operators return 0 if the comparison is false, and 1 otherwise.
 .Pp
-Unlike in a lot of languages, and for technical reasons,
+Like in a lot of languages,
 .Nm
-still evaluates both operands of
+only evaluates the left operand of
 .Sq &&
 and
-.Sq || .
+.Sq ||
+if it's equal to 0 or 1 respectively.
 .Pp
 .Ic \&!
 returns 1 if the operand was 0, and 0 otherwise.