From: bones_was_here <bones_was_here@xonotic.au>
Date: Wed, 17 Jan 2024 21:08:16 +0000 (+1000)
Subject: com_msg: optimise string and byte sequence reading
X-Git-Url: https://git.rm.cloudns.org/?a=commitdiff_plain;h=4d00367a631bdcb5b5fd7166cdd277a8d53a9a72;p=xonotic%2Fdarkplaces.git

com_msg: optimise string and byte sequence reading

Signed-off-by: bones_was_here <bones_was_here@xonotic.au>
---

diff --git a/com_msg.c b/com_msg.c
index fe29579e..aaded00d 100644
--- a/com_msg.c
+++ b/com_msg.c
@@ -340,32 +340,34 @@ float MSG_ReadBigFloat (sizebuf_t *sb)
 
 char *MSG_ReadString (sizebuf_t *sb, char *string, size_t maxstring)
 {
-	int c;
 	size_t l = 0;
+
 	// read string into sbfer, but only store as many characters as will fit
-	while ((c = MSG_ReadByte(sb)) > 0)
-		if (l < maxstring - 1)
-			string[l++] = c;
-	string[l] = '\0';
+	// if dest buffer is full sb->readcount will still be advanced to end of message string
+	while ((string[l] = MSG_ReadByte_opt(sb)) != '\0')
+		if (l < maxstring)
+			++l;
 	return string;
 }
 size_t MSG_ReadString_len (sizebuf_t *sb, char *string, size_t maxstring)
 {
-	int c;
 	size_t l = 0;
+
 	// read string into sbfer, but only store as many characters as will fit
-	while ((c = MSG_ReadByte(sb)) > 0)
-		if (l < maxstring - 1)
-			string[l++] = c;
-	string[l] = '\0';
+	// if dest buffer is full sb->readcount will still be advanced to end of message string
+	while ((string[l] = MSG_ReadByte_opt(sb)) != '\0')
+		if (l < maxstring)
+			++l;
 	return l;
 }
 
-int MSG_ReadBytes (sizebuf_t *sb, int numbytes, unsigned char *out)
+size_t MSG_ReadBytes (sizebuf_t *sb, size_t numbytes, unsigned char *out)
 {
-	int l, c;
-	for (l = 0;l < numbytes && (c = MSG_ReadByte(sb)) != -1;l++)
-		out[l] = c;
+	size_t l = 0;
+
+	// when numbytes have been read sb->readcount won't be advanced any further
+	while (l < numbytes && !sb->badread)
+		out[l++] = MSG_ReadByte_opt(sb);
 	return l;
 }
 
diff --git a/common.h b/common.h
index e85f43eb..641ed105 100644
--- a/common.h
+++ b/common.h
@@ -182,10 +182,12 @@ float MSG_ReadBigFloat (sizebuf_t *sb);
 char *MSG_ReadString (sizebuf_t *sb, char *string, size_t maxstring);
 /// Same as MSG_ReadString except it returns the number of bytes written to *string excluding the \0 terminator.
 size_t MSG_ReadString_len (sizebuf_t *sb, char *string, size_t maxstring);
-int MSG_ReadBytes (sizebuf_t *sb, int numbytes, unsigned char *out);
+size_t MSG_ReadBytes (sizebuf_t *sb, size_t numbytes, unsigned char *out);
 
 #define MSG_ReadChar(sb) ((sb)->readcount >= (sb)->cursize ? ((sb)->badread = true, -1) : (signed char)(sb)->data[(sb)->readcount++])
 #define MSG_ReadByte(sb) ((sb)->readcount >= (sb)->cursize ? ((sb)->badread = true, -1) : (unsigned char)(sb)->data[(sb)->readcount++])
+/// Same as MSG_ReadByte but with no need to copy twice (first to `int` to check for -1) so each byte can be copied directly to a string[]
+#define MSG_ReadByte_opt(sb) ((sb)->readcount >= (sb)->cursize ? ((sb)->badread = true, '\0') : (unsigned char)(sb)->data[(sb)->readcount++])
 #define MSG_ReadShort MSG_ReadLittleShort
 #define MSG_ReadLong MSG_ReadLittleLong
 #define MSG_ReadFloat MSG_ReadLittleFloat