ST20-C1 Datasheet, PDF (161/205 Pages) STMicroelectronics – Instruction Set Reference Manual

8 Instruction Set Reference
umac
unsigned multiply accumulate
Code: 21 F3
Description: Multiply Areg by Breg, adding in Creg, to form a double word result,
treating the initial values as unsigned. This can be used in forming the double length
product of Areg and Breg, with Creg as carry in.
Definition:
Areg′_unsigned ←
Breg′_unsigned ←
Creg′ ← Areg
low_word (prod)
high_word (prod)
where prod = (Breg_unsigned × Areg_unsigned) + Creg_unsigned
– the value of prod is calculated to unlimited precision
Status Register:
No effect
Comments:
Secondary instruction.
See also: mac
Chapter 5.
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