LDRD - DSP Instruction

Syntax

LDR[condition]D dest, addr_mode

where:

condition	One of 16 conditions. Refer to Condition Code Status.
dest	destination register; even numbered register followed by odd numbered register
addr_mode	Addressing Mode 3: Miscellaneous Loads and Stores
basereg	base register used by addr_mode

Description

The LDRD instruction loads ARM* core registers from addr_mode into dest . Of the two registers specified within addr_mode the first must be even and the second odd numbered. Although there are more addressing modes available than for a 2-register LDM, the address of the first word must be doubleword-aligned; i.e. divisible by 8. The condition needs to be a valid value; else the instruction is rendered an NOP.

Note

A data abort exception is generated if an invalid load or store data access is attempted. An alignment exception is generated if a system control coprocessor is implemented with alignment checking enabled and an address where bits[01:0] != 0b00. An alignment exception may be generated if a system control coprocessor is implemented with alignment checking enabled and an address where bits[02:0] != 0b100; implementation defined. The load address must be doubleword-aligned.

Addressing Mode

See Addressing Mode 3: Miscellaneous Loads and Stores

Affected Flags

N	Z	C	V	Q	S	I	F	T
T	T	T	T

Encoding

31		28	27	26	25	24	23	22	21	20	19		16	15		12	11		8	7	6	5	4	3		0
condition			0	0	0	P	U	I	W	0	basereg			dest			addr_ mode			1	1	0	1	addr_ mode

Example

1                      @.text
2                      @.globl funcldrd
3                      @.align 0
4
5                      @ * * * LDRD (Addressing Mode 3) * * *
6
7                   AREA load_store, CODE, READONLY
8
9    00000000   E3A02014   MOV   R2, #20
10   00000004   E3A03003   MOV   R3, #3
11   00000008   E5823000   STR   R3, [R2]
12   00000012   E3A05032   MOV   R5, #50
13   00000016   E3A06006   MOV   R6, #6
14   00000020   E5856000   STR   R6, [R5]
15   00000024   E18240D5   LDRD R4, [R2, R5]
16
17   00000028   E3A0603C   MOV   R6, #60
18   00000032   E3A07007   MOV   R7, #7
19   00000036   E5867000   STR   R7, [R6]
20   00000040   E3A09009   MOV   R9, #9
21   00000044   E0C680D9   LDRD R8, [R6], R9
22
23                         END

Further Information

See Addressing Mode 3: Miscellaneous Loads and Stores