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Add "print types" to bracketed symbols
Should partially cover #178 and close #270.
This allows printing numbers in different bases and without the dollar prefix
This is especially useful in macros because the dollar isnt a valid character
for symbol names, requiring heavy `STRSUB` usage.

--- a/include/asm/asm.h

+++ b/include/asm/asm.h

@@ -39,6 +39,7 @@

 extern struct sSymbol *pPCSymbol;

 extern bool oDontExpandStrings;

-size_t symvaluetostring(char *dest, size_t maxLength, char *sym);

+size_t symvaluetostring(char *dest, size_t maxLength, char *sym,

+			const char *mode);

 #endif /* RGBDS_ASM_ASM_H */

--- a/src/asm/asmy.y

+++ b/src/asm/asmy.y

@@ -1,7 +1,7 @@

 /*

  * This file is part of RGBDS.

  *

- * Copyright (c) 1997-2018, Carsten Sorensen and RGBDS contributors.

+ * Copyright (c) 1997-2019, Carsten Sorensen and RGBDS contributors.

  *

  * SPDX-License-Identifier: MIT

  */

@@ -75,7 +75,8 @@

 	out_NewAbsSection(name, secttype, org, bank);

 }

-size_t symvaluetostring(char *dest, size_t maxLength, char *sym)

+size_t symvaluetostring(char *dest, size_t maxLength, char *sym,

+			const char *mode)

 {

 	size_t length;

@@ -83,6 +84,9 @@

 		char *src = sym_GetStringValue(sym);

 		size_t i;

+		if (mode)

+			yyerror("Print types are only allowed for numbers");

+

 		for (i = 0; src[i] != 0; i++) {

 			if (i >= maxLength)

 				fatalerror("Symbol value too long to fit buffer");

@@ -94,8 +98,25 @@

 	} else {

 		uint32_t value = sym_GetConstantValue(sym);

-		int32_t fullLength = snprintf(dest, maxLength + 1, "$%X",

-					      value);

+		int32_t fullLength;

+

+		/* Special cheat for binary */

+		if (mode && !mode[0]) {

+			char binary[33]; /* 32 bits + 1 terminator */

+			char *write_ptr = binary + 32;

+			fullLength = 0;

+			binary[32] = 0;

+			do {

+				*(--write_ptr) = (value & 1) + '0';

+				value >>= 1;

+				fullLength++;

+			} while(value);

+			strncpy(dest, write_ptr, maxLength + 1);

+		} else {

+			fullLength = snprintf(dest, maxLength + 1,

+							  mode ? : "$%X",

+						      value);

+		}

 		if (fullLength < 0) {

 			fatalerror("snprintf encoding error");

--- a/src/asm/lexer.c

+++ b/src/asm/lexer.c

@@ -1,7 +1,7 @@

 /*

  * This file is part of RGBDS.

  *

- * Copyright (c) 1997-2018, Carsten Sorensen and RGBDS contributors.

+ * Copyright (c) 1997-2019, Carsten Sorensen and RGBDS contributors.

  *

  * SPDX-License-Identifier: MIT

  */

@@ -599,6 +599,7 @@

 	char ch;

 	size_t i = 0;

 	size_t length, maxLength;

+	const char *mode = NULL;

 	for (ch = *pLexBuffer;

 	     ch != '}' && ch != '"' && ch != '\n';

@@ -612,16 +613,42 @@

 				i += length;

 			else

 				fatalerror("Illegal character escape '%c'", ch);

+		} else if (ch == ':' && !mode) { /* Only grab 1st colon */

+			/* Use a whitelist of modes, which does prevent the

+			 * use of some features such as precision,

+			 * but also avoids a security flaw

+			 */

+			const char *acceptedModes = "bxXd";

+			/* Binary isn't natively supported,

+			 * so it's handled differently

+			 */

+			static const char * const formatSpecifiers[] = {

+				"", "%x", "%X", "%d"

+			};

+			/* Prevent reading out of bounds! */

+			const char *designatedMode;

+

+			if (i != 1)

+				fatalerror("Print types are exactly 1 character long");

+

+			designatedMode = strchr(acceptedModes, sym[i - 1]);

+			if (!designatedMode)

+				fatalerror("Illegal print type '%c'",

+					   sym[i - 1]);

+			mode = formatSpecifiers[designatedMode - acceptedModes];

+			/* Begin writing the symbol again */

+			i = 0;

 		} else {

 			yylex_SymbolWriteChar(sym, i++, ch);

 		}

 	}

+	/* Properly terminate the string */

 	yylex_SymbolWriteChar(sym, i, 0);

 	/* It's assumed we're writing to a T_STRING */

 	maxLength = MAXSTRLEN - index;

-	length = symvaluetostring(&dest[index], maxLength, sym);

+	length = symvaluetostring(&dest[index], maxLength, sym, mode);

 	if (*pLexBuffer == '}')

 		pLexBuffer++;

--- a/src/asm/rgbasm.5

+++ b/src/asm/rgbasm.5

@@ -1079,7 +1079,20 @@

 This will examine the type of the symbol and insert its value accordingly.

 If symbol is a string symbol, the symbols value is simply copied.

 If it's a numeric symbol, the value is converted to hexadecimal notation and

-inserted as a string.

+inserted as a string with a dollar prepended.

+.Pp

+It's possible to change the way numeric symbols are converted by specifying

+a print type like so:

+.Sy {d:symbol}

+Valid print types are:

+.Bl -column -offset indent

+.It Sy Print type Ta Sy Format Ta Sy Example

+.It Li d Ta Decimal Ta 42

+.It Li x Ta Lowercase hexadecimal Ta 2a

+.It Li X Ta Uppercase hexadecimal Ta 2A

+.It Li b Ta Binary Ta 101010

+.Pp

+Note that print types should only be used with numeric values, not strings.

 .Pp

 HINT: The

 .Sy {symbol}