Texas Instruments TMS320C67X/C67X+ DSP manual Stb, Register Offset

STB Store Byte to Memory With a 5-Bit Unsigned Constant Offset or Register Offset

				Store Byte to Memory With a 5-Bit Unsigned Constant Offset or
STB
				Register Offset
Syntax					Register Offset					Unsigned Constant Offset
					STB (.unit) src, *+baseR[offsetR]					STB (.unit) src, *+baseR[ucst5]
					.unit = .D1 or .D2
Compatibility					C62x, C64x, C67x, and C67x+ CPU
Opcode
31	29	28	27	23		22	18	17	13	12	9	8	7	6	4	3	2	1	0

creg

z

src

baseR

offsetR/ucst5

mode

0 y 0 1 1 0 1

s p

3 1555411 1

Description	Stores a byte to memory from a general-purpose register (src). Table 3−11
	(page 3-33)describes the addressing generator options. The memory
	address is formed from a base address register (baseR) and an optional offset
	that is either a register (offsetR) or a 5-bit unsigned constant (ucst5).
	offsetR and baseR must be in the same register file and on the same side as
	the .D unit used. The y bit in the opcode determines the .D unit and register
	file used: y = 0 selects the .D1 unit and baseR and offsetR from the A register
	file, and y = 1 selects the .D2 unit and baseR and offsetR from the B register
	file.
	offsetR/ucst5 is scaled by a left-shift of 0 bits. After scaling, offsetR/ucst5 is
	added to or subtracted from baseR. For the preincrement, predecrement,
	positive offset, and negative offset address generator options, the result of the
	calculation is the address to be accessed in memory. For postincrement or
	postdecrement addressing, the value of baseR before the addition or subtrac-
	tion is sent to memory.
	The addressing arithmetic that performs the additions and subtractions
	defaults to linear mode. However, for A4−A7 and for B4−B7, the mode can be
	changed to circular mode by writing the appropriate value to the AMR
	(see section 2.7.3, page 2-10).
	For STB, the 8 LSBs of the src register are stored. src can be in either register
	file, regardless of the .D unit or baseR or offsetR used. The s bit determines
	which file src is read from: s = 0 indicates src will be in the A register file and
	s = 1 indicates src will be in the B register file. The r bit should be cleared to
	0.

3-236 Instruction Set SPRU733