SPRUJ53B April 2024 – September 2024 TMS320F28P550SJ , TMS320F28P559SJ-Q1
32-Bit Floating-Point Multiply
MRa | CLA floating-point destination register (MR0 to MR3) |
#16FHi | A 16-bit immediate value that represents the upper 16-bits of an IEEE 32-bit floating-point value. The lower 16-bits of the mantissa are assumed to be all 0. |
MRb | CLA floating-point source register (MR0 to MR3) |
LSW: IIII IIII IIII IIII
MSW: 0111 0111 1000 bbaa
Multiply MRb with the floating-point value represented by the immediate operand. Store the result of the addition in MRa.
#16FHi is a 16-bit immediate value that represents the upper 16-bits of an IEEE 32-bit floating-point value. The lower 16-bits of the mantissa are assumed to be all 0. #16FHi is most useful for representing constants where the lowest 16-bits of the mantissa are 0. Some examples are 2.0 (0x40000000), 4.0 (0x40800000), 0.5 (0x3F000000), and -1.5 (0xBFC00000). The assembler accepts either a hex or float as the immediate value. That is, the value -1.5 can be represented as #-1.5 or #0xBFC0.
MRa = MRb * #16FHi:0;
This instruction can also be written as MMPYF32 MRa, MRb, #16FHi.
This instruction modifies the following flags in the MSTF register:.
Flag | TF | ZF | NF | LUF | LVF |
---|---|---|---|---|---|
Modified | No | No | No | Yes | Yes |
The MSTF register flags are modified as follows:
This is a single-cycle instruction.
; Same as example 2 but #16FHi is represented in float
MMOVIZ MR3, #2.0 ; MR3 = 2.0 (0x40000000)
MMPYF32 MR0, #3.0, MR3 ; MR0 = 3.0 * MR3 = 6.0 (0x40C00000)
MMOV32 @_X, MR0 ; Save the result in variable X
; Same as example 1 but #16FHi is represented in Hex
MMOVIZ MR3, #2.0 ; MR3 = 2.0 (0x40000000)
MMPYF32 MR0, #0x4040, MR3 ; MR0 = 0x4040 * MR3 = 6.0 (0x40C00000)
MMOV32 @_X, MR0 ; Save the result in variable X
; Given X, M, and B are IQ24 numbers:
; X = IQ24(+2.5) = 0x02800000
; M = IQ24(+1.5) = 0x01800000
; B = IQ24(-0.5) = 0xFF800000
;
; Calculate Y = X * M + B
;
;
_Cla1Task2:
;
; Convert M, X, and B from IQ24 to float
MI32TOF32 MR0, @_M ; MR0 = 0x4BC00000
MI32TOF32 MR1, @_X ; MR1 = 0x4C200000
MI32TOF32 MR2, @_B ; MR2 = 0xCB000000
MMPYF32 MR0, MR0, #0x3380 ; M = 1/(1*2^24) * iqm = 1.5 (0x3FC00000)
MMPYF32 MR1, MR1, #0x3380 ; X = 1/(1*2^24) * iqx = 2.5 (0x40200000)
MMPYF32 MR2, MR2, #0x3380 ; B = 1/(1*2^24) * iqb = -.5 (0xBF000000)
MMPYF32 MR3, MR0, MR1 ; M*X
MADDF32 MR2, MR2, MR3 ; Y=MX+B = 3.25 (0x40500000)
; Convert Y from float32 to IQ24
MMPYF32 MR2, MR2, #0x4B80 ; Y * 1*2^24
MF32TOI32 MR2, MR2 ; IQ24(Y) = 0x03400000
MMOV32 @_Y, MR2 ; store result
MSTOP ; end of task