From 01bab91678cd80dd97fc9be983bee5356e39d878 Mon Sep 17 00:00:00 2001
From: Rangi <remy.oukaour+rangi42@gmail.com>
Date: Wed, 3 Feb 2021 11:34:54 -0500
Subject: [PATCH] Implement MIN and MAX functions

Fixes #723
---
 src/asm/lexer.c   |  5 ++++-
 src/asm/parser.y  | 17 +++++++++++++++++
 src/asm/rgbasm.5  |  2 ++
 test/asm/math.asm |  8 ++++++++
 4 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/src/asm/lexer.c b/src/asm/lexer.c
index 493b2fea14..c395694e5e 100644
--- a/src/asm/lexer.c
+++ b/src/asm/lexer.c
@@ -180,6 +180,9 @@ static struct KeywordMapping {
 	{"BANK", T_OP_BANK},
 	{"ALIGN", T_OP_ALIGN},
 
+	{"MIN", T_OP_MIN},
+	{"MAX", T_OP_MAX},
+
 	{"ROUND", T_OP_ROUND},
 	{"CEIL", T_OP_CEIL},
 	{"FLOOR", T_OP_FLOOR},
@@ -496,7 +499,7 @@ 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[350] = {0}; /* Make sure to keep this correct when adding keywords! */
+} keywordDict[353] = {0}; /* Make sure to keep this correct when adding keywords! */
 
 /* Convert a char into its index into the dict */
 static inline uint8_t dictIndex(char c)
diff --git a/src/asm/parser.y b/src/asm/parser.y
index 287b0e3e82..6f43a2aa98 100644
--- a/src/asm/parser.y
+++ b/src/asm/parser.y
@@ -441,6 +441,8 @@ enum {
 %type	<nConstValue>	uconst
 %type	<nConstValue>	rs_uconst
 %type	<nConstValue>	const_3bit
+%type	<nConstValue>	min_args
+%type	<nConstValue>	max_args
 %type	<sVal>		reloc_8bit
 %type	<sVal>		reloc_8bit_no_str
 %type	<sVal>		reloc_16bit
@@ -493,6 +495,7 @@ enum {
 %token	T_OP_DEF "DEF"
 %token	T_OP_BANK "BANK"
 %token	T_OP_ALIGN "ALIGN"
+%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"
@@ -1354,6 +1357,8 @@ 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(&$$, math_Round($3));
 		}
@@ -1445,6 +1450,18 @@ const_no_str	: relocexpr_no_str {
 		}
 ;
 
+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 uconst T_COMMA uconst T_RPAREN {
 			strsubUTF8($$, sizeof($$), $3, $5, $7);
diff --git a/src/asm/rgbasm.5 b/src/asm/rgbasm.5
index e0956f2aa0..4c49200d51 100644
--- a/src/asm/rgbasm.5
+++ b/src/asm/rgbasm.5
@@ -444,6 +444,8 @@ String symbols 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
index 7411bb32d7..a225870c93 100644
--- 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