SLAU367P October 2012 – April 2020 MSP430FR5041 , MSP430FR5043 , MSP430FR50431 , MSP430FR5847 , MSP430FR58471 , MSP430FR5848 , MSP430FR5849 , MSP430FR5857 , MSP430FR5858 , MSP430FR5859 , MSP430FR5867 , MSP430FR58671 , MSP430FR5868 , MSP430FR5869 , MSP430FR5870 , MSP430FR5872 , MSP430FR58721 , MSP430FR5887 , MSP430FR5888 , MSP430FR5889 , MSP430FR58891 , MSP430FR5922 , MSP430FR59221 , MSP430FR5947 , MSP430FR59471 , MSP430FR5948 , MSP430FR5949 , MSP430FR5957 , MSP430FR5958 , MSP430FR5959 , MSP430FR5962 , MSP430FR5964 , MSP430FR5967 , MSP430FR5968 , MSP430FR5969 , MSP430FR5969-SP , MSP430FR59691 , MSP430FR5970 , MSP430FR5972 , MSP430FR59721 , MSP430FR5986 , MSP430FR5987 , MSP430FR5988 , MSP430FR5989 , MSP430FR5989-EP , MSP430FR59891 , MSP430FR5992 , MSP430FR5994 , MSP430FR59941 , MSP430FR6005 , MSP430FR6007 , MSP430FR6035 , MSP430FR6037 , MSP430FR60371 , MSP430FR6041 , MSP430FR6043 , MSP430FR60431 , MSP430FR6045 , MSP430FR6047 , MSP430FR60471 , MSP430FR6820 , MSP430FR6822 , MSP430FR68221 , MSP430FR6870 , MSP430FR6872 , MSP430FR68721 , MSP430FR6877 , MSP430FR6879 , MSP430FR68791 , MSP430FR6887 , MSP430FR6888 , MSP430FR6889 , MSP430FR68891 , MSP430FR6920 , MSP430FR6922 , MSP430FR69221 , MSP430FR6927 , MSP430FR69271 , MSP430FR6928 , MSP430FR6970 , MSP430FR6972 , MSP430FR69721 , MSP430FR6977 , MSP430FR6979 , MSP430FR69791 , MSP430FR6987 , MSP430FR6988 , MSP430FR6989 , MSP430FR69891
If the multiplier is used in interrupt service routines, its state can be saved and restored using the MPY32CTL0 register. The following code example shows how the complete multiplier status can be saved and restored to allow interruptible multiplications together with the usage of the multiplier in interrupt service routines. Because the state of the MPYSAT and MPYFRAC bits are unknown, they should be cleared before the registers are saved as shown in the code example.
; Interrupt service routine using multiplier
MPY_USING_ISR
PUSH &MPY32CTL0 ; Save multiplier mode, etc.
BIC #MPYSAT+MPYFRAC,&MPY32CTL0
; Clear MPYSAT+MPYFRAC
PUSH &RES3 ; Save result 3
PUSH &RES2 ; Save result 2
PUSH &RES1 ; Save result 1
PUSH &RES0 ; Save result 0
PUSH &MPY32H ; Save operand 1, high word
PUSH &MPY32L ; Save operand 1, low word
PUSH &OP2H ; Save operand 2, high word
PUSH &OP2L ; Save operand 2, low word
;
... ; Main part of ISR
; Using standard MPY routines
;
POP &OP2L ; Restore operand 2, low word
POP &OP2H ; Restore operand 2, high word
; Starts dummy multiplication but
; result is overwritten by
; following restore operations:
POP &MPY32L ; Restore operand 1, low word
POP &MPY32H ; Restore operand 1, high word
POP &RES0 ; Restore result 0
POP &RES1 ; Restore result 1
POP &RES2 ; Restore result 2
POP &RES3 ; Restore result 3
POP &MPY32CTL0 ; Restore multiplier mode, etc.
reti ; End of interrupt service routine