Instruction abbreviations

[nobody]

Hi,

Anyone know what the CL stands for in the last four lines of the doc
for the SHLD/SHRD instruction below? The shift count is a parameter
to a function I'm writing and I'm not sure how I'm going to get it into
the instruction when all you can use is immed8 and CL.

Michael

SHLD/SHRD - Double Precision Shift (386+)

Usage:  SHLD    dest,src,count
                SHRD    dest,src,count
        Modifies flags: CF PF SF ZF (OF,AF undefined)

SHLD shifts dest to the left count times and the bit positions
        opened are filled with the most significant bits of src.  SHRD
        shifts dest to the right count times and the bit positions
        opened are filled with the least significant bits of the second
        operand.  Only the 5 lower bits of count are used.

Clocks                  Size
        Operands                808x  286   386   486           Bytes

reg16,reg16,immed8       -     -     3     2              4
        reg32,reg32,immed8       -     -     3     2              4
        mem16,reg16,immed8       -     -     7     3              6
        mem32,reg32,immed8       -     -     7     3              6
        reg16,reg16,CL           -     -     3     3              3
        reg32,reg32,CL           -     -     3     3              3
        mem16,reg16,CL           -     -     7     4              5
        mem32,reg32,CL           -     -     7     4              5

[Frank Kotler]

The cl register - low 8 bits of ecx.

...

mov ecx, [ebp + ???] ; address of shrd count
mov cl, [ecx]
shrd eax, edx, cl
...

That what you mean?

Best,
Frank

[nobody]

Hi Frank,

Once again I guessed right, just after I posted, but thanks for the confirmation.

The count is going to be in the low end of a 64-bit integer, so could I just

mov ecx, [ecx]

or must I use the CL notation?

Michael