SPRUHM9H October 2014 – May 2024 TMS320F28075 , TMS320F28075-Q1 , TMS320F28076
Conditional Negation
MRa | CLA floating-point destination register (MR0 to MR3) |
MRb | CLA floating-point source register (MR0 to MR3) |
CNDF | Condition tested |
LSW: 0000 0000 cndf bbaa
MSW: 0111 1010 1000 0000
if (CNDF == true) {MRa = - MRb; }
else {MRa = MRb; }
CNDF is one of the following conditions:
Encode(1) | CNDF | Description | MSTF Flags Tested |
---|---|---|---|
0000 | NEQ | Not equal to zero | ZF == 0 |
0001 | EQ | Equal to zero | ZF == 1 |
0010 | GT | Greater than zero | ZF == 0 AND NF == 0 |
0011 | GEQ | Greater than or equal to zero | NF == 0 |
0100 | LT | Less than zero | NF == 1 |
0101 | LEQ | Less than or equal to zero | ZF == 1 OR NF == 1 |
1010 | TF | Test flag set | TF == 1 |
1011 | NTF | Test flag not set | TF == 0 |
1100 | LU | Latched underflow | LUF == 1 |
1101 | LV | Latched overflow | LVF == 1 |
1110 | UNC | Unconditional | None |
1111 | UNCF(2) | Unconditional with flag modification | None |
This instruction modifies the following flags in the MSTF register:
Flag | TF | ZF | NF | LUF | LVF |
---|---|---|---|---|---|
Modified | No | Yes | Yes | No | No |
This is a single-cycle instruction.
; Show the basic operation of MNEGF32
;
MMOVIZ MR0, #5.0 ; MR0 = 5.0 (0x40A00000)
MMOVIZ MR1, #4.0 ; MR1 = 4.0 (0x40800000)
MMOVIZ MR2, #-1.5 ; MR2 = -1.5 (0xBFC00000)
MMPYF32 MR3, MR1, MR2 ; MR3 = -6.0
MMPYF32 MR0, MR0, MR1 ; MR0 = 20.0
MMOVIZ MR1, #0.0
MCMPF32 MR3, MR1 ; NF = 1
MNEGF32 MR3, MR3, LT ; if NF = 1, MR3 = 6.0
MCMPF32 MR0, MR1 ; NF = 0
MNEGF32 MR0, MR0, GEQ ; if NF = 0, MR0 = -20.0
; Calculate Num/Den using a Newton-Raphson algorithum for 1/Den
; Ye = Estimate(1/X)
; Ye = Ye*(2.0 - Ye*X)
; Ye = Ye*(2.0 - Ye*X)
;
_Cla1Task1:
MMOV32 MR1, @_Den ; MR1 = Den
MEINVF32 MR2, MR1 ; MR2 = Ye = Estimate(1/Den)
MMPYF32 MR3, MR2, MR1 ; MR3 = Ye*Den
MSUBF32 MR3, #2.0, MR3 ; MR3 = 2.0 - Ye*Den
MMPYF32 MR2, MR2, MR3 ; MR2 = Ye = Ye*(2.0 - Ye*Den)
MMPYF32 MR3, MR2, MR1 ; MR3 = Ye*Den
|| MMOV32 MR0, @_Num ; MR0 = Num
MSUBF32 MR3, #2.0, MR3 ; MR3 = 2.0 - Ye*Den
MMPYF32 MR2, MR2, MR3 ; MR2 = Ye = Ye*(2.0 - Ye*Den)
|| MMOV32 MR1, @_Den ; Reload Den To Set Sign
MNEGF32 MR0, MR0, EQ ; if(Den == 0.0) Change Sign Of Num
MMPYF32 MR0, MR2, MR0 ; MR0 = Y = Ye*Num
MMOV32 @_Dest, MR0 ; Store result
MSTOP ; end of task