CPSR_c CPSR_x CPSR_s CPSR_f 分别代表什么c 控制域 (PSR [7:0]) x 扩展域掩码 (PSR [15:8]) s 状态域掩码 (PSR [23:16]) f 标志域掩码 (PSR [31:24])
MSRLoad specified fields of the CPSR or SPSR with an immediate constant, or from the contents of a general-purpose register.Syntax MSR{cond} psr_fields, #imm8MSR{cond} psr_fields, Rm Description Load fields of the Program Status Register with an immediate constant or register content. psr is either CPSR or SPSR.fields specifies a mask for the Program Status Register and can be one or more of the following:c control field mask byte (PSR [7:0]) x extension field mask byte (PSR [15:8]) s status field mask byte (PSR [23:16]) f flags field mask byte (PSR [31:24]) NoteIn user mode, only the condition flags of the CPSR (CPSR_f) can be changed. In other modes, the entire CPSR can be changed. The T bit must never change, otherwise the processor enters an unpredictable state. The SPSR register that is accessed depends on Operating Mode (current setting of the mode bits in PSR). R15 cannot be used as Rm Condition Flags If CPSR_f is specified flags are explicitly updated, otherwise condition flags are unchanged. Example MSR CPSR_f,R5 参考
1、《ARM instruction set user's guide》
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