Re: "Mini" tags to reduce the number of op codes

John Savard wrote:

On Sun, 7 Apr 2024 20:41:45 +0000, mitchalsup@aol.com (MitchAlsup1)
wrote:

In complicated if-then-else codes (and switches) I often see one inst-
ruction followed by a branch to a common point. Does your encoding deal with these efficiently ?? That is:: what happens when you jump to the
middle of a block of 36-bit instructions ??

Well, when the computer fetches a 256-bit block of code, the first
four bits indicates whether it is composed of 36-bit instructions or
28-bit instructions. So the computer knows where the instructions are;
and thus a convention can be applied, such as addressing each 36-bit
instruction by the addresses of the first seven 32-bit positions in
the block.

So, instead of using the branch target address, one rounds it down to a 256-bit boundary, reads 256-bits and looks at the first 4-bits to
determine the format, nd then uses the branch offset to pick a cont-
tainer which will become the first instruction executed.
Sounds more complicated than necessary.

In the case of 28-bit instructions, the first eight correspond to the
32-bit positions, the ninth corresponds to the last 16 bits of the
block.

John Savard