Re: Switch Case Loop Slower For Emulator

[Doug Kwan <XXXdkwanXXX@gauge.transmeta.com>]

Bryan Parkoff <BParkoff@satx.rr.com> wrote:
:     I have noticed that every programmers use Switch Case Loop for Emulator.
: Switch Case has to scan 256 opcode each time.  I think that Switch Case Loop
: is very long for scanning.  There has to be another way to reduce Switch
: Case Loop by removing too much case for scanning each opcodes.
:     It has to use clever algorithm that will reduce Intel's cycle and
: improve performance.

Most C compilers can generate a jump table for a dense switch statement.
So the time on "scanning" the opcode and dispatch is constant.
If you have a C compiler handy, try compiling into assembly
(e.g. gcc -S) and looking at the compiler output.

-Doug

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