cgram: use ASCII-only implementation of <ctype.h> functions

The function 'encode' already assumes that all letter characters are
contiguous and that there are only 26 letters of each case.  At the
moment, cgram cannot handle UTF-8 anyway since it reads the input
byte-wise, assuming that each byte is exacty one character.

1 files changed, 18 insertions, 19 deletions

diff --git a/cgram/cgram.c b/cgram/cgram.c
index 00701ab7..54b6429f 100644
--- a/cgram/cgram.c
+++ b/cgram/cgram.c
@@ -1,4 +1,4 @@
-/* $NetBSD: cgram.c,v 1.20 2021/04/25 20:19:19 rillig Exp $ */
+/* $NetBSD: cgram.c,v 1.21 2021/04/25 20:38:03 rillig Exp $ */
 
 /*-
  * Copyright (c) 2013, 2021 The NetBSD Foundation, Inc.
@@ -31,7 +31,7 @@
 
 #include <sys/cdefs.h>
 #if defined(__RCSID) && !defined(lint)
-__RCSID("$NetBSD: cgram.c,v 1.20 2021/04/25 20:19:19 rillig Exp $");
+__RCSID("$NetBSD: cgram.c,v 1.21 2021/04/25 20:38:03 rillig Exp $");
 #endif
 
 #include <assert.h>
@@ -46,42 +46,41 @@ __RCSID("$NetBSD: cgram.c,v 1.20 2021/04/25 20:19:19 rillig Exp $");
 
 #include "pathnames.h"
 
-////////////////////////////////////////////////////////////
 
-static char
-ch_toupper(char ch)
+static bool
+ch_isspace(char ch)
 {
-	return (char)toupper((unsigned char)ch);
+	return isspace((unsigned char)ch) != 0;
 }
 
-static char
-ch_tolower(char ch)
+static bool
+ch_islower(char ch)
 {
-	return (char)tolower((unsigned char)ch);
+	return ch >= 'a' && ch <= 'z';
 }
 
 static bool
-ch_isalpha(char ch)
+ch_isupper(char ch)
 {
-	return isalpha((unsigned char)ch) != 0;
+	return ch >= 'A' && ch <= 'Z';
 }
 
 static bool
-ch_islower(char ch)
+ch_isalpha(char ch)
 {
-	return islower((unsigned char)ch) != 0;
+	return ch_islower(ch) || ch_isupper(ch);
 }
 
-static bool
-ch_isspace(char ch)
+static char
+ch_toupper(char ch)
 {
-	return isspace((unsigned char)ch) != 0;
+	return ch_islower(ch) ? (char)(ch - 'a' + 'A') : ch;
 }
 
-static bool
-ch_isupper(char ch)
+static char
+ch_tolower(char ch)
 {
-	return isupper((unsigned char)ch) != 0;
+	return ch_isupper(ch) ? (char)(ch - 'A' + 'a') : ch;
 }
 
 static int