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Altera_Forum
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15 years ago

lpm_add_sub output bits - MSB or LSB?

Hi, I looked through the help for lpm_add_sub megafunction <http://quartushelp.altera.com/9.1/mergedProjects/hdl/mega/mega_file_lpm_add_sub.htm> and couldn't really figure out if the input/output...
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Altera_Forum
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15 years ago

The general rule is MSBs for any arithmetic function.

Why are you using lpm_add_sub anyway when

c <= a + b; in VHDL (and similar is available in verilog) is much much simpler to write and understand.