From: lkcl Date: Wed, 27 Apr 2022 11:46:34 +0000 (+0100) Subject: (no commit message) X-Git-Tag: opf_rfc_ls005_v1~2563 X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=3eae6ac8db4d9b5d09b7d9ab344e9baef73538cd;p=libreriscv.git --- diff --git a/openpower/sv/biginteger/analysis.mdwn b/openpower/sv/biginteger/analysis.mdwn index 6aebf874b..2583d7941 100644 --- a/openpower/sv/biginteger/analysis.mdwn +++ b/openpower/sv/biginteger/analysis.mdwn @@ -381,8 +381,8 @@ However when moving to 64-bit digits (desirable because the algorithm is `O(N^2)`) this in turn means that the estimate has to be computed from a *128* bit dividend and a 64-bit divisor. Such an operation simply does not exist in most Scalar 64-bit ISAs. Although Power ISA -comes close with `divdeu` placing the dividend in the upper half -of a 128-bit computation the lower half is zeros. Again Power ISA +comes close with `divdeu`, by placing the dividend in the upper half +of a 128-bit computation, the lower half is zero. Again Power ISA has a Packed SIMD instruction `vdivuq` which is a 128/128 (quad) divide, not a 128/64. Some investigation into soft-implementations of 128/128 or 128/64 divide show it to be typically