Texas Instruments MSP50C6xx manual Assembler Directives, Examples

Assembler

5.4 Assembler

5.4.1Assembler Directives

Assembler directives are texts which have special meaning to the assembler. Some of these directives are extremely helpful during conditional compiling, debugging, adding additional features to existing codes, multiple hardware development, code release etc. Other directives are an essential part of the assembler to initialize variables with values, assigning symbols to memory locations, assigning origin of a program, etc. The assembler directives that start with a # (hash) sign cannot have spaces before the directive. The following assembler directives are recognized by the assembler. Some of these assembler directives use expressions and symbols. These are explained below:

expression can be any numeric value. Addition, subtraction, and multiplication are allowed.

Examples:

(128 / 2 ) * 2 + (220 / 5) + 2 + *0x200 equates to 0xAE + *0x200, where *0x200 indicates data memory location.

(2 * 2 / 2 + ((5 * 2) * 3) / 2) (0x0F & 0x04) equates to 0x15. Note that bitwise AND (& operator) and OR ( operator) operations are allowed.

(10 * 2) + 5 * *0x120 expression points to data memory content at 0x120, multiplies decimal 5 to it, and finally adds decimal 20. Note that a space is required between successive asterisks (*). Also note that *0x120 indicates content of memory location at 0x120 hex.

The grammar for expressions and symbols are as follows:

number:	number 0 1 2 3 4 5 6 7 8 9
expression:	number
	expression + expression
	expression – expression
	expression * expression
	expression / expression
	expression expression
	expression & expression
	~expression
	–expression
	+expression
	*expression

Code Development Tools 5-11