32-Bit Hardware Multiplier Operation
9-13
32-Bit Hardware Multiplier
9−4 shows the flow for 32-bit saturation used for 16
×
16 bit
multiplications and the flow for 64-bit saturation used in all other cases.
Primarily, the saturated results depends on the carry bit MPYC and the most
significant bit of the result. Secondly, if the fractional mode is enabled it
depends also on the two most significant bits of the unshift result; i.e., the result
that is read with fractional mode disabled.
Figure 9−4. Saturation Flow Chart
32−bit Saturation
MPYC=0 and
unshifted RES1,
bit 15=1
Overflow:
RES3 unchanged
RES2 unchanged
RES1 = 07FFFh
RES0 = 0FFFFh
Yes
No
MPYC=1 and
unshifted RES1,
bit 15=0
Underflow:
RES3 unchanged
RES2 unchanged
RES1 = 08000h
RES0 = 00000h
MPYFRAC = 1
Yes
No
No
Yes
unshifted RES1,
bit 15=0 and
bit 14=1
Overflow:
RES3 unchanged
RES2 unchanged
RES1 = 07FFFh
RES0 = 0FFFFh
Yes
No
unshifted RES1,
bit 15=1 and
bit 14=0
Underflow:
RES3 unchanged
RES2 unchanged
RES1 = 08000h
RES0 = 00000h
Yes
No
32−bit Saturation
completed
64−bit Saturation
MPYC=0 and
unshifted RES3,
bit 15=1
Overflow:
RES3 = 07FFFh
RES2 = 0FFFFh
RES1 = 0FFFFh
RES0 = 0FFFFh
Yes
No
MPYC=1 and
unshifted RES3,
bit 15=0
Underflow:
RES3 = 08000h
RES2 = 00000h
RES1 = 00000h
RES0 = 00000h
MPYFRAC = 1
Yes
No
No
Yes
unshifted RES3,
bit 15=0 and
bit 14=1
Yes
No
unshifted RES3,
bit 15=1 and
bit 14=0
Yes
No
64−bit Saturation
completed
Overflow:
RES3 = 07FFFh
RES2 = 0FFFFh
RES1 = 0FFFFh
RES0 = 0FFFFh
Underflow:
RES3 = 08000h
RES2 = 00000h
RES1 = 00000h
RES0 = 00000h
Note: Saturation in Fractional Mode
In case of multiplying −1.0 x −1.0 in fractional mode, the result of +1.0 is out
of range, thus, the saturated result will give the most positive result.
Содержание MSP430x4xx Family
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Страница 340: ...7 8 Supply Voltage Supervisor ...
Страница 348: ...8 8 16 Bit Hardware Multiplier ...
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Страница 400: ...10 28 DMA Controller ...
Страница 428: ...13 10 Basic Timer1 ...
Страница 466: ...15 24 Timer_A ...
Страница 522: ...17 30 USART Peripheral Interface UART Mode ...
Страница 544: ...18 22 USART Peripheral Interface SPI Mode ...
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Страница 746: ...26 28 ADC12 ...