Texas Instruments MSP50C614 Subs Subtract Accumulataor String, Assembly Language Instructions 177

Individual Instruction Descriptions

4.14.81 SUBS			Subtract Accumulataor String
Syntax
	[label]	name		dest, src, src1	Clock, clk	Word, w		With RPT, clk	Class
		SUBS		An[~], An, {adrs}	Table 4±46			Table 4±46	1a
		SUBS		An[~], An[~], pma16	ns+4		2	N/R	32b
		SUBS		An[~], An, An~	ns+2		1	nR+2	3
		SUBS		An[~], An~, An	ns+2		1	nR+2	3
		SUBS²		An[~], An[~], PH	1		1	1	3

²This instruction ignores the string count, executing only once but maintains the CF and ZF status of the previous multi- ply or shift operation as if the sequence was a single string. This instruction should immediately follow one of the fol- lowing class 1b instructions: MOVAPH, MULAPL, MULSPL, SHLTPL, SHLSPL, and SHLAPL. An interrupt can occur between one of these instructions and this instruction. An interrupt may cause an incorrect result. Also, single stepping is not allowed for this instruction. An in this instruction should be the same as An in one of the listed class 1b instruc- tion. Offsets are allowed. See Section 4.8 for detail.

Execution	[premodify AP if mod specified]
	dest ⇐ dest ± src						(for two operands)
	dest ⇐ src ± src1						(for three operands)
	PC ⇐ PC + w
Flags Affected	dest is An:						OF, SF, ZF, CF are set accordingly
	src1 is {adrs}:						TAG bit is set accordingly
Opcode
Instructions		16	15	14	13	12		11	10	9		8	7	6	5	4		3	2	1	0
SUBS An[~], An, {adrs}		0	0	0	1	~A		1	1		An						adrs
		x			dma16 (for direct) or offset16 (long relative) [see section 4.13]
SUBS An[~], An[~], pma16		1	1	1	0	0		1	1		An		0	1	0	0		1	1	A~	~A
SUBS An[~], An, An~		1	1	1	0	0		1	1		An		0	0	1	0		0	0	0	~A
SUBS An[~], An~, An		1	1	1	0	0		1	1		An		0	0	1	0		0	0	1	~A
SUBS An[~], An[~], PH		1	1	1	0	0		1	1		An		0	1	1	0		0	0	A~	~A
Description	Subtract the value of the src string from value of the dest string and store the
	result in the dest string. If three operands are specified, then subtract value of
	src1 string from value of src string (i.e., src±src1) and store result in dest string.

Note that, substraction is performed in 2's complement and therefore the CF (carry flag) may get set even when subtracting a smaller value from a large value.

Assembly Language Instructions 4-177