Re: Any more graceful way to saturate adds?

On 11 Apr, 08:41, Terje Mathisen  <spamt...@[EMAIL PROTECTED]
> wrote:
> What's wrong with the obvious approach?
>
>   add al,dl     ; Carry set if it overflows!
>   sbb al,al     ; AL = 0xff if overflow
>   or dl,al      ; Turns any overflow into 0xff

Very neat.  Now, what about the signed case (saturating at +127 or
-128)?  The best I've managed is:

    add al,dl     ; Signed addition
    jno ok        ; Jump if no overflow
    sbb al,al     ; al is 0x00 or 0xff
    xor al,127    ; Saturate to -128 or +127
ok:

Richard.
http://www.rtrussell.co.uk/
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