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From: | Stefan Monnier |
Subject: | Re: Removing assumption of unsigned long pixel values for colours |
Date: | Mon, 06 May 2019 12:51:24 -0400 |
User-agent: | Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux) |
> The original plan was to avoid any conversion at all (no conversion > necessary on the Emacs side to create the struct of doubles); would you > still consider the difference between no conversion and 4 conversions to > be negligible? That which costs is when we can't use a pre-existing struct and need to allocate a new struct and copy the values to it (with or without conversion). If we need to do the copy anyway, the added cost of a conversion along the way is very likely to be negligible. The rule of thumb is that arithmetic operations are free (contrary to data movement). [ Which also means that "the conversion" can be costly in the case where the need for the conversion in turn requires allocation of a new struct. ] Stefan
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