Implement MIN and MAX functions

Fixes gbdev#723
Rangi42 · Jun 24, 2021 · 21dca2d · 21dca2d
1 parent 6d2db2e
commit 21dca2d
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Showing 4 changed files with 31 additions and 1 deletion.
diff --git a/src/asm/lexer.c b/src/asm/lexer.c
@@ -183,6 +183,9 @@ static struct KeywordMapping {
 	{"SIZEOF", T_OP_SIZEOF},
 	{"STARTOF", T_OP_STARTOF},
 
+	{"MIN", T_OP_MIN},
+	{"MAX", T_OP_MAX},
+
 	{"ROUND", T_OP_ROUND},
 	{"CEIL", T_OP_CEIL},
 	{"FLOOR", T_OP_FLOOR},
@@ -595,7 +598,7 @@ struct KeywordDictNode {
 	uint16_t children[0x60 - ' '];
 	struct KeywordMapping const *keyword;
 /* Since the keyword structure is invariant, the min number of nodes is known at compile time */
-} keywordDict[365] = {0}; /* Make sure to keep this correct when adding keywords! */
+} keywordDict[368] = {0}; /* Make sure to keep this correct when adding keywords! */
 
 /* Convert a char into its index into the dict */
 static uint8_t dictIndex(char c)

diff --git a/src/asm/parser.y b/src/asm/parser.y
@@ -485,6 +485,8 @@ enum {
 %type	<constValue>	uconst
 %type	<constValue>	rs_uconst
 %type	<constValue>	const_3bit
+%type	<constValue>	min_args
+%type	<constValue>	max_args
 %type	<expr>		reloc_8bit
 %type	<expr>		reloc_8bit_no_str
 %type	<expr>		reloc_8bit_offset
@@ -537,6 +539,7 @@ enum {
 %token	T_OP_BANK "BANK"
 %token	T_OP_ALIGN "ALIGN"
 %token	T_OP_SIZEOF "SIZEOF" T_OP_STARTOF "STARTOF"
+%token	T_OP_MIN "MIN" T_OP_MAX "MAX"
 %token	T_OP_SIN "SIN" T_OP_COS "COS" T_OP_TAN "TAN"
 %token	T_OP_ASIN "ASIN" T_OP_ACOS "ACOS" T_OP_ATAN "ATAN" T_OP_ATAN2 "ATAN2"
 %token	T_OP_FDIV "FDIV"
@@ -1481,6 +1484,8 @@ relocexpr_no_str : scoped_anon_id { rpn_Symbol(&$$, $1); }
 
 			lexer_ToggleStringExpansion(true);
 		}
+		| T_OP_MIN T_LPAREN min_args T_RPAREN { rpn_Number(&$$, $3); }
+		| T_OP_MAX T_LPAREN max_args T_RPAREN { rpn_Number(&$$, $3); }
 		| T_OP_ROUND T_LPAREN const T_RPAREN {
 			rpn_Number(&$$, fix_Round($3));
 		}
@@ -1561,6 +1566,18 @@ const_no_str	: relocexpr_no_str { $$ = rpn_GetConstVal(&$1); }
 const_8bit	: reloc_8bit { $$ = rpn_GetConstVal(&$1); }
 ;
 
+min_args	: const
+		| min_args T_COMMA const {
+			$$ = $1 < $3 ? $1 : $3;
+		}
+;
+
+max_args	: const
+		| max_args T_COMMA const {
+			$$ = $1 > $3 ? $1 : $3;
+		}
+;
+
 string		: T_STRING
 		| T_OP_STRSUB T_LPAREN string T_COMMA const T_COMMA uconst T_RPAREN {
 			size_t len = strlenUTF8($3);

diff --git a/src/asm/rgbasm.5 b/src/asm/rgbasm.5
@@ -476,6 +476,8 @@ String equates are not expanded within the parentheses.
 .It Fn ISCONST arg Ta Returns 1 if Ar arg Ap 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.
+.It Fn MIN args... Ta Returns the minimum operand, given at least one numeric operand.
+.It Fn MAX args... Ta Returns the maximum operand, given at least one numeric operand.
 .El
 .Sh SECTIONS
 Before you can start writing code, you must define a section.

diff --git a/test/asm/math.asm b/test/asm/math.asm
@@ -16,6 +16,14 @@ ENDM
 	test (v 1) << (v 30) == (v $4000_0000)
 	test (v 2)**(v 30) == (v $4000_0000)
 
+	assert MIN(42) == 42
+	assert MIN(-10, 10) == -10
+	assert MIN(2, 1, 4, 3) == 1
+
+	assert MAX(42) == 42
+	assert MAX(-10, 10) == 10
+	assert MAX(2, 1, 4, 3) == 4
+
 	assert DIV(5.0, 2.0) == 2.5
 	assert DIV(-5.0, 2.0) == -2.5
 	assert DIV(-5.0, 0.0) == $8000_0000