From 6e2e2f1db7b8bac7c9deb8317ed8ab30c56f545c Mon Sep 17 00:00:00 2001
From: Rangi <35663410+Rangi42@users.noreply.github.com>
Date: Sat, 26 Sep 2026 19:30:05 -0400
Subject: [PATCH] Add `%A`/`%a` uppercase/lowercase string format specifiers
 (#2165)

---
 man/rgbasm.5                   |  4 +++-
 src/asm/format.cpp             | 19 ++++++++++++++-----
 test/asm/case-conversion.asm   | 13 +++++++++++++
 test/asm/string-formatting.asm |  5 +++--
 test/asm/string-formatting.out |  3 ++-
 5 files changed, 35 insertions(+), 9 deletions(-)
 create mode 100644 test/asm/case-conversion.asm

diff --git a/man/rgbasm.5 b/man/rgbasm.5
index 06de1bf5..dfa32684 100644
--- a/man/rgbasm.5
+++ b/man/rgbasm.5
@@ -251,7 +251,9 @@ Valid types are:
 .It Ql b Ta Binary Ta 101010
 .It Ql o Ta Octal Ta 52
 .It Ql f Ta Fixed-point Ta 1234.56789
-.It Ql s Ta String Ta string contents
+.It Ql s Ta String Ta String contents
+.It Ql A Ta Uppercase string Ta UPPERCASED STRING
+.It Ql a Ta Lowercase string Ta lowercased string
 .El
 .Pp
 Examples:
diff --git a/src/asm/format.cpp b/src/asm/format.cpp
index 364d91fc..ad29adf5 100644
--- a/src/asm/format.cpp
+++ b/src/asm/format.cpp
@@ -11,7 +11,8 @@
 #include <string.h>
 #include <string>
 
-#include "util.hpp" // parseNumber
+#include "helpers.hpp" // RANGE
+#include "util.hpp"    // parseNumber, toUpper, toLower
 
 #include "asm/main.hpp" // options
 #include "asm/warning.hpp"
@@ -72,6 +73,8 @@ size_t FormatSpec::parseSpec(char const *spec) {
 	case 'o':
 	case 'f':
 	case 's':
+	case 'A':
+	case 'a':
 		++i;
 		type = c;
 		break;
@@ -130,11 +133,17 @@ void FormatSpec::appendString(std::string &str, std::string const &value) const
 	if (hasPrec) {
 		error("Formatting string with fractional precision");
 	}
-	if (useType != 's') {
+	if (useType != 's' && useType != 'A' && useType != 'a') {
 		error("Formatting string as type '%c'", useType);
 	}
 
-	std::string useValue = exact ? escapeString(value) : value;
+	std::string useValue = value;
+	if (useType == 'A' || useType == 'a') {
+		std::transform(RANGE(useValue), useValue.begin(), useType == 'A' ? toUpper : toLower);
+	}
+	if (exact) {
+		useValue = escapeString(useValue);
+	}
 	size_t valueLen = useValue.length();
 	size_t totalLen = width > valueLen ? width : valueLen;
 	size_t padLen = totalLen - valueLen;
@@ -168,8 +177,8 @@ void FormatSpec::appendNumber(std::string &str, uint32_t value) const {
 	if (useType != 'f' && hasPrec) {
 		error("Formatting type '%c' with fractional precision", useType);
 	}
-	if (useType == 's') {
-		error("Formatting number as type 's'");
+	if (useType == 's' || useType == 'A' || useType == 'a') {
+		error("Formatting number as type '%c'", useType);
 	}
 
 	char signChar = sign; // 0 or ' ' or '+'
diff --git a/test/asm/case-conversion.asm b/test/asm/case-conversion.asm
new file mode 100644
index 00000000..03e46a9d
--- /dev/null
+++ b/test/asm/case-conversion.asm
@@ -0,0 +1,13 @@
+; ASCII
+assert STRUPR("camelCase") === "CAMELCASE"
+assert STRLWR("camelCase") === "camelcase"
+assert STRFMT("%s", "camelCase") === "camelCase"
+assert STRFMT("%A", "camelCase") === "CAMELCASE"
+assert STRFMT("%a", "camelCase") === "camelcase"
+
+; UTF-8
+assert STRUPR("ÇA a été ?") === "ÇA A éTé ?"
+assert STRLWR("ÇA a été ?") === "Ça a été ?"
+assert STRFMT("%s", "ÇA a été ?") === "ÇA a été ?"
+assert STRFMT("%A", "ÇA a été ?") === "ÇA A éTé ?"
+assert STRFMT("%a", "ÇA a été ?") === "Ça a été ?"
diff --git a/test/asm/string-formatting.asm b/test/asm/string-formatting.asm
index cc009ade..691a5b72 100644
--- a/test/asm/string-formatting.asm
+++ b/test/asm/string-formatting.asm
@@ -2,7 +2,7 @@ def n equ 300
 def m equ -42
 def f equ -123.0456
 def pi equ 3.14159
-def s equs "hello"
+def s equs "Hello!"
 def t equs "\"\\t\" is '\t'"
 def u equs "\t\r\0\n"
 
@@ -10,7 +10,8 @@ def u equs "\t\r\0\n"
 	println "<{u:m}> <{+3d:m}> <{#016o:m}>"
 	println "<{f:pi}> <{06.f:f}> <{.10f:f}>"
 	println "\"{#-20s:t}\", \"{#20s:t}\", \"{20s:t}\""
-	println "{#s:u}"
+	println "{s:s} {A:s} {a:s}"
+	println "{#s:u} {#A:u} {#a:u}"
 
 macro foo
 	println "\1 <{\1}>"
diff --git a/test/asm/string-formatting.out b/test/asm/string-formatting.out
index f000a17c..1e7425e6 100644
--- a/test/asm/string-formatting.out
+++ b/test/asm/string-formatting.out
@@ -2,5 +2,6 @@
 <4294967254> <-42> <&000037777777726>
 <3.14159> <-00123> <-123.0455932617>
 "\"\\t\" is '\t'     ", "     \"\\t\" is '\t'", "         "\t" is '	'"
-\t\r\0\n
+Hello! HELLO! hello!
+\t\r\0\n \t\r\0\n \t\r\0\n
 -6d:n <300   >