Intel i86W Manual page 166

PROGRAMMING EXAMPLES
9.4 INTEGER MULTIPLY
A 32-bit integer multiply is implemented in Example 9-5 by transferring the operands to
floating-point registers and using the
fmlow
instruction. If the result is referenced in the
next instruction, eleven clocks are required. Seven clocks can be overlapped with other
operations.
II INTEGER MULTIPLY
II
The multiplier is in r4
II
The multiplicand is in r5
II The product is left in rb
II
The registers f2, f4, and fb are used as temporaries.
ixfr r4, f2
ixfr r5, f4
II
Two core instructions can be inserted here without penalty.
fmlow.dd f4, f2, fb
II
Four core instructions can be inserted here without penalty.
fxfr fb, rb
II
One core instruction can be inserted here without penalty.
Example 9-5. Integer Multiply
9-4