Texas Instruments MSP430x1xx - Manual (Page 100)

Hardware Multiplier Software Restrictions
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6.5.3 Hardware Multiplier Software Restrictions—MACS
The multiplier does not automatically detect underflow or overflow in the
MACS mode. An overflow occurs when the sum of the accumulator register
and the result of the signed multiplication exceed the maximum binary range.
The binary range of the accumulator for positive numbers is 0 to 2 31 –1
(7FFF FFFFh) and for negative numbers is –1 (0FFFF FFFFh) to –2 31
(8000 0000h). An overflow occurs when the sum of two negative numbers
yields a result that is in the range given above for a positive number. An under-
flow occurs when the sum of two positive numbers yields a result that is in the
range for a negative number.
The maximum number of successive MACS instructions without underflow or
overflow is limited by the individual application and should be determined us-
ing a worst-case calculation. Care should then be exercised to not exceed the
maximum number or to handle the conditions accordingly.