From: Dmitry Antipov
> Sent: 28 June 2023 11:45
>
> On 6/28/23 11:24, David Laight wrote:
>
> > What are the (u16) casts for?
>
> Well, this is a kind of a C language purism intended to silence
> warning: conversion from ‘int’ to ‘u16’ {aka ‘short unsigned int’} may change value [-Wconversion]
> observed with W=123.
The problem is that the casts can hide more than just a value being truncated.
In this case the compiler even knows the values don't overflow.
FWIW I've seen generated code for:
*cp++ = (unsigned char)(value & 0xff);
that masked the value with 0xff once for the & a second time for
the cast and then stored the low byte.
I don't think modern gcc will do that, but a dumb compiler will.
If -Wconversion bleats about these sort of assignments it just
needs permanently disabling (or deleting from the compiler!).
David
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