shithub: rgbds

--- a/include/asm/rpn.h

+++ b/include/asm/rpn.h

@@ -54,6 +54,7 @@

 		  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 *tzSym);

--- a/src/asm/asmy.y

+++ b/src/asm/asmy.y

@@ -543,6 +543,7 @@

 %left	T_OP_FLOOR

 %token	T_OP_HIGH T_OP_LOW

+%token	T_OP_ISCONST

 %left	T_OP_STRCMP

 %left	T_OP_STRIN

@@ -1301,6 +1302,7 @@

 		| T_OP_NOT relocexpr %prec NEG	{ rpn_UNNOT(&$$, &$2); }

 		| T_OP_HIGH '(' relocexpr ')'	{ rpn_HIGH(&$$, &$3); }

 		| T_OP_LOW '(' relocexpr ')'	{ rpn_LOW(&$$, &$3); }

+		| T_OP_ISCONST '(' relocexpr ')'{ rpn_ISCONST(&$$, &$3); }

 		| T_OP_BANK '(' scoped_id ')' {

 			/* '@' is also a T_ID, it is handled here. */

 			rpn_BankSymbol(&$$, $3);

--- a/src/asm/globlex.c

+++ b/src/asm/globlex.c

@@ -460,6 +460,7 @@

 	{"high", T_OP_HIGH},

 	{"low", T_OP_LOW},

+	{"isconst", T_OP_ISCONST},

 	{"strcmp", T_OP_STRCMP},

 	{"strin", T_OP_STRIN},

--- a/src/asm/rgbasm.5

+++ b/src/asm/rgbasm.5

@@ -553,7 +553,7 @@

.Pp

 One of the best features of an assembler is the ability to write macros for it.

 Macros also provide a method of passing arguments to them and they can then react to the input using

-.Sy IF

+.Ic IF

 constructs.

.Pp

 .Bd -literal -offset indent

@@ -1317,6 +1317,9 @@

 has been defined.

 .It Fn HIGH arg Ta Returns the top 8 bits of the operand if Ar arg No is a label or constant, or the top 8-bit register if it is a 16-bit register.

 .It Fn LOW arg Ta Returns the bottom 8 bits of the operand if Ar arg No is a label or constant, or the bottom 8-bit register if it is a 16-bit register Pq Cm AF No isn't a valid register for this function .

+.It Fn ISCONST arg Ta Returns 1 if Ar arg Ns No 's value is known by RGBASM (e.g. if it can be an argument to

+.Ic IF ) ,

+or 0 if only RGBLINK can compute its value.

.El

 .Sh MISCELLANEOUS

 .Ss Changing options while assembling

--- a/src/asm/rpn.c

+++ b/src/asm/rpn.c

@@ -506,6 +506,14 @@

+void rpn_ISCONST(struct Expression *expr, const struct Expression *src)

+{

+	rpn_Init(expr);

+	expr->nVal = rpn_isKnown(src);

+	expr->isKnown = true;

+	expr->isSymbol = false;

+}

 void rpn_UNNEG(struct Expression *expr, const struct Expression *src)

 	*expr = *src;

--- /dev/null

+++ b/test/asm/isconst.asm

@@ -1,0 +1,29 @@

+TEST_NUM = 0

+test_expr: MACRO

+TEST_NUM = TEST_NUM + 1

+IS_CONST = ISCONST(\1)

+	PRINTT "Test #{d:TEST_NUM}: ISCONST reports {IS_CONST}\n"

+	IF (\1) || 1 ; Only test if the expression can be evaluated

+		WARN "Test #{d:TEST_NUM}: Compile-time constant"

+	ENDC

+ENDM

+	test_expr 1

+	test_expr UnknownLabel

+SECTION "fixed", WRAM0[$CAFE]

+FixedLabel:

+	ds 42

+	test_expr FixedLabel

+	test_expr @ - FixedLabel

+SECTION "floating", WRAMX

+FloatingLabel:

+	ds 69

+	test_expr FloatingLabel

+	test_expr @ - FloatingLabel

--- /dev/null

+++ b/test/asm/isconst.err

@@ -1,0 +1,13 @@

+warning: isconst.asm(14) -> isconst.asm::test_expr(10): [-Wuser]

+    Test #1: Compile-time constant

+ERROR: isconst.asm(15) -> isconst.asm::test_expr(9):

+    Expected constant expression: 'UnknownLabel' is not constant at assembly time

+warning: isconst.asm(21) -> isconst.asm::test_expr(10): [-Wuser]

+    Test #3: Compile-time constant

+warning: isconst.asm(22) -> isconst.asm::test_expr(10): [-Wuser]

+    Test #4: Compile-time constant

+ERROR: isconst.asm(28) -> isconst.asm::test_expr(9):

+    Expected constant expression: 'FloatingLabel' is not constant at assembly time

+warning: isconst.asm(29) -> isconst.asm::test_expr(10): [-Wuser]

+    Test #6: Compile-time constant

+error: Assembly aborted (2 errors)!

--- /dev/null

+++ b/test/asm/isconst.out

@@ -1,0 +1,6 @@

+Test #1: ISCONST reports $1

+Test #2: ISCONST reports $0

+Test #3: ISCONST reports $1

+Test #4: ISCONST reports $1

+Test #5: ISCONST reports $0

+Test #6: ISCONST reports $1