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Cortex-A8 Technical Reference Manual - ARM Information Center

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16.2.6 Miscellaneous data-processing instructions<br />

16.2.7 Status register access instructions<br />

16.2.8 Load/store instructions<br />

The miscellaneous data-processing instructions include PK, SAT, SEL.<br />

Table 16-7 shows the operation of miscellaneous data-processing instructions.<br />

Instruction Cycle Timing<br />

Table 16-7 Miscellaneous data-processing instructions<br />

Shift type Cycles Source1 Source2 Source3 Source4 Result1 Result2<br />

SAT a<br />

1 Rm:E1 [Rd:E2] - - Rd:E1/E2 -<br />

CLZ 1 Rm:E2 [Rd:E2] - - Rd:E2 -<br />

USAD 1 Rm:E1 Rn:E1 [Rd:E2] - Rd:E5 -<br />

PKT a 1 Rm:E1 Rn:E1 [Rd:E2] - Rd:E1/E2 -<br />

SEL 1 Rm:E1 Rn:E1 [Rd:E2] - Rd:E2 -<br />

a. If conditional, result is not available until E2.<br />

The MRS, MSR, and CPS instructions modify the CPSR and SPSR registers. Table 16-8 shows the<br />

operation of the status register access instructions.<br />

Table 16-8 Status register access instructions<br />

Access type Cycles Source1 Source2 Source3 Source4 Result1 Result2<br />

MRS a<br />

MSR b<br />

1 Rd:E2 - - - Rd:E1/E2 -<br />

1 Rm:E1 Rd:E2 - - - -<br />

CPS b 1 - - - - - -<br />

SETEND b 1 - - - - - -<br />

a. Serialize before the instruction.<br />

b. Serialize between micro-operations. Force pipeline flush if updating CPSR. Serialize only for SPSR<br />

updates.<br />

There are many key characteristics that define different load/store instructions including the<br />

addressing mode, the data type, data size, whether or not register writeback is enabled, and<br />

indexing mode. Table 16-9 on page 16-8 and Table 16-10 on page 16-8 specify the timing for<br />

various load/store instruction types based on each of these characteristics, but only if that<br />

characteristic has an effect on timing. For example, data type and all data sizes except 64-bit<br />

offset do not affect instruction timing.<br />

<strong>ARM</strong> DDI 0344K Copyright © 2006-2010 <strong>ARM</strong> Limited. All rights reserved. 16-7<br />

ID060510 Non-Confidential

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