Deprecate LDH with $00-$FF (#1575)

gbdev · Dec 11, 2024 · c1c5b10 · c1c5b10
1 parent f44de0c
commit c1c5b10
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Showing 6 changed files with 50 additions and 5 deletions.
diff --git a/include/asm/rpn.hpp b/include/asm/rpn.hpp
@@ -53,7 +53,7 @@ struct Expression {
 	void makeUnaryOp(RPNCommand op, Expression &&src);
 	void makeBinaryOp(RPNCommand op, Expression &&src1, Expression const &src2);
 
-	void makeCheckHRAM();
+	bool makeCheckHRAM();
 	void makeCheckRST();
 
 	void checkNBit(uint8_t n) const;

diff --git a/man/rgbasm-old.5 b/man/rgbasm-old.5
@@ -267,6 +267,23 @@ Instead, use
 .Ql LDH [C], A
 and
 .Ql LDH A, [C] .
+.Ss LDH [n8], A and LDH A, [n8]
+Deprecated in 0.9.0.
+.Pp
+.Ql LDH
+used to treat "addresses" from
+.Ad $00
+to
+.Ad $FF
+as if they were the low byte of an address from
+.Ad $FF00
+to
+.Ad $FFFF .
+.Pp
+Instead, use
+.Ql LDH [n16], A
+and
+.Ql LDH A, [n16] .
 .Ss rgbasm -i
 Deprecated in 0.6.0, removed in 0.8.0.
 .Pp

diff --git a/src/asm/parser.y b/src/asm/parser.y
@@ -1949,13 +1949,23 @@ z80_ldd:
 
 z80_ldh:
 	Z80_LDH MODE_A COMMA op_mem_ind {
-		$4.makeCheckHRAM();
+		if ($4.makeCheckHRAM()) {
+			warning(
+			    WARNING_OBSOLETE,
+			    "LDH is deprecated with values from $00 to $FF; use $FF00 to $FFFF\n"
+			);
+		}
 
 		sect_ConstByte(0xF0);
 		sect_RelByte($4, 1);
 	}
 	| Z80_LDH op_mem_ind COMMA MODE_A {
-		$2.makeCheckHRAM();
+		if ($2.makeCheckHRAM()) {
+			warning(
+			    WARNING_OBSOLETE,
+			    "LDH is deprecated with values from $00 to $FF; use $FF00 to $FFFF\n"
+			);
+		}
 
 		sect_ConstByte(0xE0);
 		sect_RelByte($2, 1);

diff --git a/src/asm/rpn.cpp b/src/asm/rpn.cpp
@@ -568,16 +568,20 @@ void Expression::makeBinaryOp(RPNCommand op, Expression &&src1, Expression const
 	}
 }
 
-void Expression::makeCheckHRAM() {
+bool Expression::makeCheckHRAM() {
 	isSymbol = false;
 	if (!isKnown()) {
 		*reserveSpace(1) = RPN_HRAM;
 	} else if (int32_t val = value(); val >= 0xFF00 && val <= 0xFFFF) {
 		// That range is valid, but only keep the lower byte
 		data = val & 0xFF;
-	} else if (val < 0 || val > 0xFF) {
+	} else if (val >= 0 && val <= 0xFF) {
+		// That range is valid, but deprecated
+		return true;
+	} else {
 		error("Source address $%" PRIx32 " not between $FF00 to $FFFF\n", val);
 	}
+	return false;
 }
 
 void Expression::makeCheckRST() {

diff --git a/src/link/patch.cpp b/src/link/patch.cpp
@@ -356,6 +356,12 @@ static int32_t computeRPNExpr(Patch const &patch, std::vector<Symbol> const &fil
 					isError = true;
 				}
 				value = 0;
+			} else if (value >= 0 && value <= 0xFF) {
+				warning(
+				    patch.src,
+				    patch.lineNo,
+				    "LDH is deprecated with values from $00 to $FF; use $FF00 to $FFFF"
+				);
 			}
 			value &= 0xFF;
 			break;

diff --git a/test/asm/deprecated-ldio.err b/test/asm/deprecated-ldio.err
@@ -1,3 +1,7 @@
+warning: deprecated-ldio.asm(5): [-Wobsolete]
+    LDH is deprecated with values from $00 to $FF; use $FF00 to $FFFF
+warning: deprecated-ldio.asm(6): [-Wobsolete]
+    LDH is deprecated with values from $00 to $FF; use $FF00 to $FFFF
 warning: deprecated-ldio.asm(8): [-Wobsolete]
     LD [C], A is deprecated; use LDH [C], A
 warning: deprecated-ldio.asm(9): [-Wobsolete]
@@ -10,6 +14,10 @@ warning: deprecated-ldio.asm(15): [-Wobsolete]
     LDIO is deprecated; use LDH
 warning: deprecated-ldio.asm(16): [-Wobsolete]
     LDIO is deprecated; use LDH
+warning: deprecated-ldio.asm(20): [-Wobsolete]
+    LDH is deprecated with values from $00 to $FF; use $FF00 to $FFFF
+warning: deprecated-ldio.asm(21): [-Wobsolete]
+    LDH is deprecated with values from $00 to $FF; use $FF00 to $FFFF
 warning: deprecated-ldio.asm(23): [-Wobsolete]
     LD [C], A is deprecated; use LDH [C], A
 warning: deprecated-ldio.asm(24): [-Wobsolete]