Adding a doc for eval functions.

docs/eval_functions.md

@@ -0,0 +1,47 @@
+# Eval Functions
+
+Eval Functions are used like symbols in expressions but are always followed by parenthesis with optional arguments.
+
+### DEFINED, DEF
+
+	.if .def(symbol)
+	.endif
+
+Evaluates to 1 if the symbol has been defined or 0 if it has not been encountered to this point in the current assembly.
+
+### REFERENCED
+
+	.if .referenced(symbol)
+	.endif
+
+Evaluates to 1 if the symbol has been referenced in the current assembly, the symbol should be defined at this point.
+
+### BLANK
+
+	.if .blank()
+	.endif
+
+Evaluates to 1 if the contents within the parenthesis is empty, primarily for use within macros.
+
+### CONST
+
+	if .const(symbol)
+	.endif
+
+Evaluates to 1 if the symbol has been declared CONST, the symbol should be defined at this point.
+
+### SIZEOF
+
+	STRUCT Module {
+		word Init
+		word Update
+		word Shutdown
+	}
+
+	ds SIZEOF( Module )
+
+Returns the byte size of a given struct.
+
+### TRIGSIN
+
+Not implemented, experimental math feature, currently returns 0

docs/readme.md

@@ -37,12 +37,24 @@ result.
 
 ## Command Line Options
 
+Controls the assembler for the entire file
+
 See [Command Line Options](command_line_options.md)
 
 ## Directives
 
+Controls the assembler on a line basis
+
 See [Directives](directives.md)
 
+## Eval Functions
+
+Functions that returns values for use in expressions.
+
+See [Eval Functions](eval_functions.md)
+
 ## Macro examples
 
+Some info about the included example x65macro.i file.
+
 See [Macro Samples](macro_samples.md)