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Altera_Forum
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19 years ago

Nios2 1.01 hadware multiply instruction

Hi everyone In my nios folder i see C:\altera\kits\nios2\components\altera_nios_multiply\ this component I want use multiply instruction in my Cyclone based board But with NIOS2 1.01 s...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
19 years ago

The ELF patching utility is able to change MUL, MULXUU, MULXSU, and MULXSS instructions to use your custom instruction. However, it is not able to change the MULI instructions; they have a 16-bit immediate field which custom instructions don't support. The MULI instructions are used when your source code multiples a number by a constant.

So, is this patch still going to meet your needs?

BTW, I'm curious about why you don't upgrade to a new version of Nios II that includes support for multiply instructions using logic elements (and take multiple cycles to compute).