Compiler/TMS320F280049: CLA compiler adds MMOVIZ instruction for 16-bit write

For this expression ...

Dmitry Sharihin said:

EPwm1Regs.AQCTLA.all = my_constant

Please show the declaration of "all" and "my_constant".. With that, we should be able to construct a small test case that generates the same assembly sequence, and then explain it.

Thanks and regards,

-George

Hello, George

/** \brief Test code for CLA compiler, marked as __attribute__((interrupt)) in header file */
void inverter_clainit(void) {
    EPwm1Regs.AQCTLA.all = (1 << 8);
}

Where AQCTLA is 

struct AQCTLA_BITS {                    // bits description
    uint16_t ZRO:2;                       // 1:0 Action Counter = Zero
    uint16_t PRD:2;                       // 3:2 Action Counter = Period
    uint16_t CAU:2;                       // 5:4 Action Counter = Compare A Up
    uint16_t CAD:2;                       // 7:6 Action Counter = Compare A Down
    uint16_t CBU:2;                       // 9:8 Action Counter = Compare B Up
    uint16_t CBD:2;                       // 11:10 Action Counter = Compare B Down
    uint16_t rsvd1:4;                     // 15:12 Reserved
};

union AQCTLA_REG {
    uint16_t  all;
    struct  AQCTLA_BITS  bit;
};

This structure is part of F28004x Device Support Library, so I've attached file f28004x_epwm.h where this struct is defined.f28004x_epwm.h

Generated assembly code looks like this:

;***************************************************************
;* TMS320x280xx Control Law Accelerator C/C++ Codegen Unix v18.1.3.LTS *
;* Date/Time created: Wed Aug  8 07:56:36 2018                 *
;***************************************************************
	.compiler_opts --abi=coffabi --cla_support=cla2 --diag_wrap=off --float_support=fpu32 --hll_source=on --mem_model:code=flat --mem_model:data=large --object_format=coff --silicon_version=28 --symdebug:none --tmu_support=tmu0

;...

;***************************************************************
;* FNAME: _inverter_clainit             FR SIZE:   0           *
;*                                                             *
;* FUNCTION ENVIRONMENT                                        *
;*                                                             *
;* FUNCTION PROPERTIES                                         *
;*                            0 Auto,  0 SOE     *
;***************************************************************

_inverter_clainit:
        MMOVIZ    MR0,#0                ; [CPU_FPU] |21| 
        MMOVXI    MR0,#256              ; [CPU_FPU] |21| 
        MMOV16    @_EPwm1Regs+64,MR0    ; [CPU_FPU] |21| 
        MNOP      ; [CPU_FPU] 
        MNOP      ; [CPU_FPU] 
        MSTOP     ; [CPU_FPU] 
        ; ireturn occurs ; [] 
;**************************************************************
;* UNDEFINED EXTERNAL REFERENCES                              *
;**************************************************************
	.global	_EPwm1Regs