Added .asize and .isize pseudo variables

These pseudo variables will return the size of the accumulator/index
in bits.

For the 65816 instruction set .ASIZE/.ISIZE will return either 8 or 16,
depending on the current size of the operand in immediate addressing
mode.

For all other CPU instruction sets, .ASIZE/.ISIZE will always return 8.

For example:

	; Reverse Subtract with Accumulator
	; A = memory - A
	.macro rsb param
		.if .asize = 8
			eor	#$ff
		.else
			eor	#$ffff
		.endif
		sec
		adc	param
	.endmacro

src/ca65/expr.c

@@ -1099,6 +1099,15 @@ static ExprNode* Factor (void)
             N = Function (FuncAddrSize);
             break;
 
+	case TOK_ASIZE:
+            if (GetCPU() != CPU_65816) {
+                N = GenLiteralExpr (8);
+            } else {
+	        N = GenLiteralExpr (ExtBytes [AM65I_IMM_ACCU] * 8);
+            }
+	    NextTok ();
+	    break;
+
         case TOK_BLANK:
             N = Function (FuncBlank);
             break;
@@ -1132,6 +1141,15 @@ static ExprNode* Factor (void)
             N = Function (FuncIsMnemonic);
             break;
 
+	case TOK_ISIZE:
+            if (GetCPU() != CPU_65816) {
+                N = GenLiteralExpr (8);
+            } else {
+                N = GenLiteralExpr (ExtBytes [AM65I_IMM_INDEX] * 8);
+            }
+            NextTok ();
+	    break;
+
         case TOK_LOBYTE:
             N = Function (FuncLoByte);
             break;

src/ca65/pseudo.c

@@ -1967,6 +1967,7 @@ static CtrlDesc CtrlCmdTab [] = {
     { ccNone,           DoUnexpected    },      /* .ADDRSIZE */
     { ccNone,           DoAlign         },
     { ccNone,           DoASCIIZ        },
+    { ccNone,           DoUnexpected    },      /* .ASIZE */
     { ccNone,           DoAssert        },
     { ccNone,           DoAutoImport    },
     { ccNone,           DoUnexpected    },      /* .BANK */
@@ -2041,6 +2042,7 @@ static CtrlDesc CtrlCmdTab [] = {
     { ccNone,           DoIncBin        },
     { ccNone,           DoInclude       },
     { ccNone,           DoInterruptor   },
+    { ccNone,           DoUnexpected    },      /* .ISIZE */
     { ccNone,           DoUnexpected    },      /* .ISMNEMONIC */
     { ccNone,           DoInvalid       },      /* .LEFT */
     { ccNone,           DoLineCont      },

src/ca65/scanner.c

@@ -139,6 +139,7 @@ struct DotKeyword {
     { ".ALIGN",         TOK_ALIGN               },
     { ".AND",           TOK_BOOLAND             },
     { ".ASCIIZ",        TOK_ASCIIZ              },
+    { ".ASIZE",         TOK_ASIZE               },
     { ".ASSERT",        TOK_ASSERT              },
     { ".AUTOIMPORT",    TOK_AUTOIMPORT          },
     { ".BANK",          TOK_BANK                },
@@ -224,6 +225,7 @@ struct DotKeyword {
     { ".INCBIN",        TOK_INCBIN              },
     { ".INCLUDE",       TOK_INCLUDE             },
     { ".INTERRUPTOR",   TOK_INTERRUPTOR         },
+    { ".ISIZE",         TOK_ISIZE               },
     { ".ISMNEM",        TOK_ISMNEMONIC          },
     { ".ISMNEMONIC",    TOK_ISMNEMONIC          },
     { ".LEFT",          TOK_LEFT                },

src/ca65/token.h

@@ -126,6 +126,7 @@ typedef enum token_t {
     TOK_ADDRSIZE,
     TOK_ALIGN,
     TOK_ASCIIZ,
+    TOK_ASIZE,
     TOK_ASSERT,
     TOK_AUTOIMPORT,
     TOK_BANK,
@@ -200,6 +201,7 @@ typedef enum token_t {
     TOK_INCBIN,
     TOK_INCLUDE,
     TOK_INTERRUPTOR,
+    TOK_ISIZE,
     TOK_ISMNEMONIC,
     TOK_LEFT,
     TOK_LINECONT,