ARM instruction Set

MRS and MSR Instructions

The status flag in the MRS (move PSR to general-purpose Register) procedure status register (program state REGISTER,PSR) is read into the Universal Register, MSR (move general-purpose Register to PSR) writes the flag to the program status register. These two instructions can be used in the current program status register (CPSR) or in the Saved program status register (SPSR). For example:

MRS R0, Cpsrmrs R1, SPSRMSR PSR, R7

BIC directives

The BIC is used to place the specified bits in the register 0 (bit clear). For example:

 and  not #0xFF000000

The high 8 bits of the R3 register are zeroed and the result is stored in the R2 register.

ARM instruction Set