DescriptionResetTypeNameBit/Field
EPSR ICI / IT status
These bits, along with bits 15:10, contain the Interruptible-Continuable
Instruction (ICI) field for an interrupted load multiple or store multiple
instruction or the execution state bits of the IT instruction.
When EPSR holds the ICI execution state, bits 26:25 are zero.
The If-Then block contains up to four instructions following an IT
instruction. Each instruction in the block is conditional. The conditions
for the instructions are either all the same, or some can be the inverse
of others. See the Cortex™-M4 instruction set chapter in the ARM®
Cortex™-M4 Devices Generic User Guide (literature number ARM DUI
0553A) for more information.
The value of this field is only meaningful when accessing PSR or EPSR.
Note that these EPSR bits cannot be accessed using MRS and MSR
instructions but the definitions are provided to allow the stacked (E)PSR
value to be decoded within an exception handler.
0x0ROICI / IT26:25
EPSR Thumb State
This bit indicates the Thumb state and should always be set.
The following can clear the THUMB bit:
■ The BLX, BX and POP{PC} instructions
■ Restoration from the stacked xPSR value on an exception return
■ Bit 0 of the vector value on an exception entry or reset
Attempting to execute instructions when this bit is clear results in a fault
or lockup. See “Lockup” on page 125 for more information.
The value of this bit is only meaningful when accessing PSR or EPSR.
1ROTHUMB24
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
0x00ROreserved23:20
Greater Than or Equal Flags
See the description of the SEL instruction in the Cortex™-M4 instruction
set chapter in the ARM® Cortex™-M4 Devices Generic User Guide
(literature number ARM DUI 0553A) for more information.
The value of this field is only meaningful when accessing PSR or APSR.
0x0RWGE19:16
June 18, 201494
Texas Instruments-Production Data
The Cortex-M4F Processor
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