Texas Instruments MSP50C6xx manual Class 3 Instruction Encoding, Class 3 Instruction Description

Instruction Classification

between the accumulator and the MR, SV, or PH register. As with all accumula- tor referenced instructions, string operations are possible as well as premodi- fication of one of 4 indirectly referenced accumulator pointer registers (AP).

Table 4–19. Class 3 Instruction Encoding

Bit	16	15	14	13	12	11	10	9		8	7	6		5	4	3	2	1	0
Class 3	1	1	1	0	0	next A			An				C3				0	A~	~A

Table 4–20. Class 3 Instruction Description

		C3			Mnemonic	Description
0	0	0	0	0	NEGAC An[~], An[~] [, next A]	Store the 2’s complement of the source accumulator
					NEGACS An[~], An[~]	(A~=0 or 1) to the destination accumulator (~A=0 or 1).
						ALU status is modified.
0	0	0	0	1	NOTAC An[~], An[~] [, next A]	Place the 1’s complement of the source accumulator
					NOTACS An[~], An[~]	(A~=0 or 1) into the destination accumulator (~A=0 or 1).
						ALU status is modified.
0	0	0	1	0	MOV An[~], *An[~] [, next A]	Look up a value in program memory addressed by
					MOVS An[~], *An[~]	accumulator (A~=0 or 1). Place the lookup value into the
						accumulator (~A=0 or 1). The lookup address is
						post–incremented in the DP register. ALU status is
						modified based on the lookup value.
0	0	0	1	1	ZAC An[~] [, next A]	Zero accumulator (~A=0 or 1). ALU status is modified.
					ZACS An[~]
0	0	1	0	0	SUB An[~], An, An~ [, next A]	Subtract offset accumulator from accumulator (A~=0) or
					SUB An[~], An~, An [, next A]	subtract accumulator from offset accumulator (A~=1).
					SUBS An[~], An, An~	Store the result in accumulator (~A=0 or 1). ALU status is
					SUBS An[~], An~, An	modified.
0	0	1	0	1	ADD An[~], An~, An [, next A]	Add accumulator to offset accumulator and store result to
					ADDS An[~], An~, An	accumulator (~A=0 or 1). ALU status is modified.
0	0	1	1	0	SHLAC An[~], An[~] [, next A]	Shift accumulator left 1 bit and store the result into
					SHLACS An[~], An[~]	accumulator(~A=0) or offset accumulator (~A=1). The
						LSB is set to zero and the MSB is stored in a carryout
						status bit. ALU status is modified.
0	0	1	1	1	MOV An, An~ [, next A]	Copy accumulator (A~=0 or 1) to accumulator (~A=0 or 1).
					MOVS An, An~	ALU status is modified.

†These instructions have a special 1 word string operations when string mode is selected. The instructions ignore the string count, executing only once but maintain the carry and comparison to zero operation of the previous arithmetic operation as if the sequence of the previous string instruction and this instruction execution was a part of a larger string operation.

Assembly Language Instructions 4-31