Embedded Systems: An Integrated Approach by Pearson

362 EMBEDDED SYSTEMS

i)  e source and destination registers are 32 bits in length. If the product is longer

than 32 bits, only the lower bits are preserved in the destination register.

ii) Immediate data cannot be used as a source operand.

iii) If the multiplicand and multiplier are signed numbers, it is up to the programmer to

identify a logic to interpret the sign of the product.

iv)  e instruction can be made conditional.

Example

MUL R1, R2, R3 ;R1 = R2 × R3

MULS R1, R2, R3 ;R1 = R2 × R3 and fl ags are also set

MULSEQ R3, R2, R1 ;R1 = R2 × R3 is done only if the Z = 1

;(because of the EQ suffi x)

;because of the S suffi x, fl ags are updated

MULEQ R4, R3, R5 ;if Z = 1, R4 = R3 × R5

10.11.2 | Multiply and Accumulate

 e format ...