
© G.N. Khan ARM Processors/Cores – EE8205: Embedded Computer Systems Page: 30
PSR: Program Status Register
Divided into three bit fields
• Application Program Status Register (APSR)
• Interrupt Program Status Register (IPSR)
• Execution Program Status Register (EPSR)
Q-bit is the sticky saturarion bit and supports two rarely used
instructions (SSAT and USAT)
SSAT{cond} Rd, #sat, Rm{, shift}
• EPSR holds the exception number is exception processing.
• ICI/IT bits holds the state information of for IT block instructions or
instructions that are suspended during interrupt processing.
• T bit is always 1 to indicate Thumb instructions.
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