Texas Instruments MSP50C6xx Flag Addressing, TF1, *0x20, Or TF2, *R6+0x02, XOR TF1, *R6+0x20

Instruction Syntax and Addressing Modes

4.3.7Flag Addressing

This addressing mode addresses only the 17th bit (the flag/tag bit) located in data memory. This addressing applies to Class 8a instructions as explained in section 4.4. Using flag addressing, the flag bit can be loaded or saved. In addition, various logical operations can be performed without affecting the re- maining 16 bits of the selected word. Two addressing modes are provided. The first addressing mode, global flag addressing, has bit 0 set to zero and a six bit field (b1–b6) that defines the flag word address. The second mode, relative flag addressing, has bit 0 set to one and a 6-bit field (b1–b6) that defines the flag address relative to R6 (see Figure 4–2). In other words, the, i.e., effective address = (contents of R6) + (6-bit offset). In flag addressing, R6 contains the address that points to the 17th bit. This should not be confused with byte ad- dresses and word addresses.

Figure 4–2. Relative Flag Addressing

R6

PAGE register

Address

6-Bit positive offset

+

		Operand
Syntax:
	name {dest}, {src}
Global Flag:	name TFn, dma6
	name dma6, TFn
Relative Flag:	name TFn, *R6+offset6
	name *R6+offset6, TFn
Example 4.3.24	MOV *0x02, TF2

Take the test flag 2 bit (TF2 in the status register) and place it into the 17th bit of the data memory location 0x02.

Example 4.3.25 AND TF1, *0x20

AND the test flag 1 bit (TF1 in status register) with the 17th bit of the data memory location 0x20 and store the result in the TF1 bit of the STAT.

Example 4.3.26 OR TF2, *R6+0x02

OR the test flag 2 bit (TF2 in status register) with the 17th bit of the data memory location *(R6+0x02) and store the result in the TF2 bit in of the status register. So, if R6=0x0100, then relative flag address is 0x0102.

Example 4.3.27 XOR TF1, *R6+0x20

XOR the test flag 1 bit (TF1 in status register) with the 17th bit of the data memory location *(R6+0x20) and store the result in TF1 bit of the status register. So, if R6=0x0100, then relative flag address is 0x0120.

Assembly Language Instructions 4-19