Texas Instruments TMS320C67X/C67X+ DSP manual Lddw, Or Register Offset

LDDW Load Doubleword From Memory With an Unsigned Constant Offset or Register Offset

				Load Doubleword From Memory With an Unsigned Constant Offset
LDDW
				or Register Offset
Syntax					Register Offset					Unsigned Constant Offset
					LDDW (.unit) *+baseR[offsetR], dst					LDDW (.unit) *+baseR[ucst5], dst
					.unit = .D1 or .D2
Compatibility					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

dst

baseR

offsetR/ucst5

mode

1 y 1 1 0 0 1 s p

3 1 5 5 5 4 1 1 1

Description	Loads a doubleword from memory into a register pair dst_o:dst_e. 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).
	Both 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 the regis-
	ter file used: y = 0 selects the .D1 unit and the baseR and offsetR from the
	A register file, and y = 1 selects the .D2 unit and baseR and offsetR from the
	B register file. The s bit determines the register file into which the dst is loaded:
	s = 0 indicates that dst is in the A register file, and s = 1 indicates that dst is
	in the B register file. The r bit has a value of 1 for the LDDW instruction. The
	dst field must always be an even value because the LDDW instruction loads
	register pairs. Therefore, bit 23 is always zero.
	The offsetR/ucst5 is scaled by a left-shift of 3 to correctly represent double-
	words. 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 shifted value
	of baseR before the addition or subtraction is the address to be accessed in
	memory.

3-128 Instruction Set SPRU733