Refactored the code for "substr" script function

* fixed the crashing bug and added a new behavior.

Changed the error message due to missing critter frame (again):
* replaced the interruption with printing the error message to in-game
message window.

artifacts/scripting/sfall function notes.txt

@@ -248,7 +248,10 @@ Some utility/math functions are available:
 - you can use this to search for a substring in a string like this: strlen(get_array(string_split(haystack, needle), 0))
 
 > string substr(string, start, length)
-- cuts a substring from a string starting at "start" up to "length" characters. If start is negative - it indicates starting position from the end of the string (for example substr("test", -2, 2) will return last 2 charactes: "st"). If length is negative - it means so many characters will be omitted from the end of string (example: substr("test", 0, -2) will return string without last 2 characters: "te")
+- cuts a substring from a string starting at "start" up to "length" characters. The first character position starts with 0 (zero).
+- If start is negative - it indicates starting position from the end of the string (for example substr("test", -2, 2) will return last 2 charactes: "st").
+- If length is negative - it means so many characters will be omitted from the end of string (example: substr("test", 0, -2) will return string without last 2 characters: "te").
+- If length is zero - it will return a string from the starting position to the end of the string **New behavior** for sfall 4.2.2/3.8.22
 
 > int strlen(string string)
 - returns string length

sfall/DebugEditor.cpp

@@ -313,12 +313,15 @@ artNotExist:
 		push eax;
 		push artDbgMsg;
 		call debug_printf_;
-		add  esp, 8;
-		cmp  isDebug, 0;
-		jz   skip;
-		int  3; // break program
-skip:
-		retn;
+		mov  eax, [esp + 0x124 - 0x1C + 12]; // filename
+		push eax;
+		push artDbgMsg;
+		lea  eax, [esp + 0x124 - 0x124 + 20]; // buf
+		push eax;
+		call sprintf_;
+		add  esp, 20;
+		lea  eax, [esp + 4];
+		jmp  display_print_;
 	}
 }
 
@@ -357,7 +360,7 @@ static void DebugModePatch() {
 		if (iniGetInt("Debugging", "HideObjIsNullMsg", 0, ddrawIniDef)) {
 			MakeJump(0x453FD2, dbg_error_hack);
 		}
-		// prints a debug message about missing art file for critters and interrupts game execution
+		// prints a debug message about missing art file for critters to debug.log and the message window
 		HookCall(0x419B65, art_data_size_hook);
 
 		dlogr(" Done", DL_INIT);

sfall/LoadGameHook.cpp

@@ -472,9 +472,9 @@ end:
 
 static void __declspec(naked) DialogHook() {
 	__asm {
-		cmp dword ptr [esp + 0x14], 0x45A5C9; // call from op_gsay_end_
-		je  changeMode;
-		jmp gdProcess_;
+		test inLoop, DIALOG; // check bit flag
+		jz   changeMode;
+		jmp  gdProcess_;
 changeMode:
 		or inLoop, DIALOG;
 		call gdProcess_;

sfall/ScriptExtender.h

@@ -94,7 +94,7 @@ void _stdcall AddTimerEventScripts(DWORD script, long time, long param);
 void _stdcall RemoveTimerEventScripts(DWORD script, long param);
 void _stdcall RemoveTimerEventScripts(DWORD script);
 
-char* _stdcall mysubstr(const char* str, int pos, int length);
+char* _stdcall Substring(const char* str, int startPos, int length);
 
 // variables
 static char reg_anim_combat_check = 1;

sfall/ScriptOps/ScriptArrays.hpp

@@ -151,7 +151,7 @@ callsubstr:
 		push 1;
 		push edi;
 		push eax;
-		call mysubstr;
+		call Substring;
 		mov edx, eax; // result substring
 		mov ebx, VAR_TYPE_STR; // result type
 		jmp end;

sfall/ScriptOps/ScriptUtils.hpp

@@ -513,30 +513,40 @@ end:
 	}
 }
 
-char* _stdcall mysubstr(const char* str, int pos, int length) {
-	char* newstr;
-	int srclen;
-	srclen = strlen(str);
-	if (pos < 0)
-		pos = srclen + pos;
-	if (length < 0)
-		length = srclen - pos + length;
-	if (pos >= srclen)
-		length = 0;
-	else if (length + pos > srclen)
-		length = srclen - pos;
-	newstr = new char[length + 1];
-	if (length > 0)
-		memcpy(newstr, &str[pos], length);
-	newstr[length] = '\0';
-	return newstr;
+static char* tempTextBuf = nullptr;
+
+char* _stdcall Substring(const char* str, int startPos, int length) {
+	int len = strlen(str);
+
+	if (startPos < 0) {
+		startPos += len; // start from end
+		if (startPos < 0) startPos = 0;
+	}
+	if (length < 0) {
+		length += len - startPos; // cutoff at end
+		if (length == 0) {
+			return "";
+		} else if (length < 0) {
+			length = -length; // length can't be negative
+		}
+	}
+	// check position
+	if (startPos >= len) return ""; // start position is out of string length, return empty string
+	if (length == 0 || length + startPos > len) {
+		length = len - startPos; // set the correct length, the length of characters goes beyond the end of the string
+	}
+
+	if (tempTextBuf) delete[] tempTextBuf;
+	tempTextBuf = new char[length + 1];
+	memcpy(tempTextBuf, &str[startPos], length);
+	tempTextBuf[length] = '\0';
+	return tempTextBuf;
 }
 
 static DWORD _stdcall mystrlen(const char* str) {
 	return strlen(str);
 }
 
-static char* sprintfbuf = nullptr;
 static char* _stdcall mysprintf(const char* format, DWORD value, DWORD valueType) {
 	valueType = valueType & 0xFFFF; // use lower 2 bytes
 	int fmtlen = strlen(format);
@@ -601,87 +611,37 @@ static char* _stdcall mysprintf(const char* format, DWORD value, DWORD valueType
 	} else {
 		buflen = j + 30; // numbers
 	}
-	if (sprintfbuf) {
-		delete[] sprintfbuf;
+	if (tempTextBuf) {
+		delete[] tempTextBuf;
 	}
-	sprintfbuf = new char[buflen + 1];
+	tempTextBuf = new char[buflen + 1];
 	if (valueType == VAR_TYPE_FLOAT) {
-		_snprintf(sprintfbuf, buflen, newfmt, *(float*)(&value));
+		_snprintf(tempTextBuf, buflen, newfmt, *(float*)(&value));
 	} else {
-		_snprintf(sprintfbuf, buflen, newfmt, value);
+		_snprintf(tempTextBuf, buflen, newfmt, value);
 	}
-	sprintfbuf[buflen] = '\0'; // just in case
+	tempTextBuf[buflen] = '\0'; // just in case
 	delete[] newfmt;
-	return sprintfbuf;
+	return tempTextBuf;
+}
+
+static void _stdcall op_substr2() {
+	const ScriptValue &strArg = opHandler.arg(0),
+					  &startArg = opHandler.arg(1),
+					  &lenArg = opHandler.arg(2);
+
+	if (strArg.isString() && startArg.isInt() && lenArg.isInt()) {
+		const char* str = strArg.strValue();
+		if (*str != '\0') str = Substring(str, startArg.rawValue(), lenArg.rawValue());
+		opHandler.setReturn(str);
+	} else {
+		OpcodeInvalidArgs("substr");
+		opHandler.setReturn(-1);
+	}
 }
 
 static void __declspec(naked) op_substr() {
-	__asm {
-		pushad;
-		mov edi, eax;
-		call interpretPopShort_;
-		push eax;
-		mov eax, edi;
-		call interpretPopLong_; // length
-		push eax;
-		mov eax, edi;
-		call interpretPopShort_;
-		push eax;
-		mov eax, edi;
-		call interpretPopLong_; // position
-		push eax;
-		mov eax, edi;
-		call interpretPopShort_;
-		push eax;
-		mov eax, edi;
-		call interpretPopLong_; // string
-		push eax;
-
-		movzx eax, word ptr [esp+12];
-		cmp eax, VAR_TYPE_INT;
-		jne fail;
-		movzx eax, word ptr [esp+20];
-		cmp eax, VAR_TYPE_INT;
-		jne fail;
-		movzx eax, word ptr [esp+4];
-		cmp eax, VAR_TYPE_STR2;
-		je next1;
-		cmp eax, VAR_TYPE_STR;
-		jne fail;
-next1:
-		mov eax, edi;
-		mov edx, [esp+4];
-		mov ebx, [esp];
-		call interpretGetString_;
-		mov ebx, [esp+16];
-		mov edx, [esp+8];
-		push ebx;
-		push edx;
-		push eax;
-		call mysubstr;
-		mov edx, eax;
-		mov eax, edi;
-		call interpretAddString_;
-		mov edx, eax;
-		mov eax, edi;
-		call interpretPushLong_;
-		mov edx, VAR_TYPE_STR;
-		mov eax, edi;
-		call interpretPushShort_;
-		jmp end;
-fail:
-		xor edx, edx;
-		dec edx;
-		mov eax, edi;
-		call interpretPushLong_;
-		mov edx, VAR_TYPE_INT;
-		mov eax, edi;
-		call interpretPushShort_;
-end:
-		add esp, 24;
-		popad;
-		retn;
-	}
+	_WRAP_OPCODE(op_substr2, 3, 1)
 }
 
 static void __declspec(naked) op_strlen() {