Date: Mon, 7 Dec 2015 23:50:25 -0500 From: Michael McConville <mmcco@mykolab.com> To: araujo@FreeBSD.org Cc: freebsd-current <freebsd-current@freebsd.org> Subject: Re: [PATCH] XOR uses Message-ID: <20151208045025.GA17698@thinkpad.swarthmore.edu> In-Reply-To: <CAOfEmZiwq0vH6vN34c=3-0PJL1gTNjOjksNyQR1Ojve%2BuPbRYA@mail.gmail.com> References: <20151208031327.GA17554@thinkpad.swarthmore.edu> <CAOfEmZiwq0vH6vN34c=3-0PJL1gTNjOjksNyQR1Ojve%2BuPbRYA@mail.gmail.com>
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Marcelo Araujo wrote:
> What would be the advantage of it?
Just clarity and readability.
> I still prefer explicit than implicit. The current code is much more
> readable.
I very much disagree. XOR is a basic binary operation, like AND and OR.
I don't understand what's more explicit about using 4x the code to
reimplement it every time. I don't feel strongly about the patches fate,
though.
> 2015-12-08 11:13 GMT+08:00 Michael McConville <mmcco@mykolab.com>:
>
> > A minor simplification patch:
> >
> >
> > Index: sys/arm/allwinner/a10_gpio.c
> > ===================================================================
> > --- sys/arm/allwinner/a10_gpio.c (revision 291978)
> > +++ sys/arm/allwinner/a10_gpio.c (working copy)
> > @@ -356,10 +356,7 @@
> > sc = device_get_softc(dev);
> > A10_GPIO_LOCK(sc);
> > data = A10_GPIO_READ(sc, A10_GPIO_GP_DAT(bank));
> > - if (data & (1 << pin))
> > - data &= ~(1 << pin);
> > - else
> > - data |= (1 << pin);
> > + data ^= (1 << pin);
> > A10_GPIO_WRITE(sc, A10_GPIO_GP_DAT(bank), data);
> > A10_GPIO_UNLOCK(sc);
> >
> > Index: sys/arm/altera/socfpga/socfpga_gpio.c
> > ===================================================================
> > --- sys/arm/altera/socfpga/socfpga_gpio.c (revision 291978)
> > +++ sys/arm/altera/socfpga/socfpga_gpio.c (working copy)
> > @@ -336,10 +336,7 @@
> >
> > GPIO_LOCK(sc);
> > reg = READ4(sc, GPIO_SWPORTA_DR);
> > - if (reg & (1 << i))
> > - reg &= ~(1 << i);
> > - else
> > - reg |= (1 << i);
> > + reg ^= (1 << i);
> > WRITE4(sc, GPIO_SWPORTA_DR, reg);
> > GPIO_UNLOCK(sc);
> >
> > Index: sys/arm/rockchip/rk30xx_gpio.c
> > ===================================================================
> > --- sys/arm/rockchip/rk30xx_gpio.c (revision 291978)
> > +++ sys/arm/rockchip/rk30xx_gpio.c (working copy)
> > @@ -375,10 +375,7 @@
> > return (EINVAL);
> > RK30_GPIO_LOCK(sc);
> > data = RK30_GPIO_READ(sc, RK30_GPIO_SWPORT_DR);
> > - if (data & (1U << pin))
> > - data &= ~(1U << pin);
> > - else
> > - data |= (1U << pin);
> > + data ^= (1U << pin);
> > RK30_GPIO_WRITE(sc, RK30_GPIO_SWPORT_DR, data);
> > RK30_GPIO_UNLOCK(sc);
> >
> > Index: sys/arm/samsung/exynos/exynos5_pad.c
> > ===================================================================
> > --- sys/arm/samsung/exynos/exynos5_pad.c (revision 291978)
> > +++ sys/arm/samsung/exynos/exynos5_pad.c (working copy)
> > @@ -722,10 +722,7 @@
> >
> > GPIO_LOCK(sc);
> > reg = READ4(sc, bank.port, bank.con + 0x4);
> > - if (reg & (1 << pin_shift))
> > - reg &= ~(1 << pin_shift);
> > - else
> > - reg |= (1 << pin_shift);
> > + reg ^= (1 << pin_shift);
> > WRITE4(sc, bank.port, bank.con + 0x4, reg);
> > GPIO_UNLOCK(sc);
> >
> > Index: sys/dev/nand/nandsim_ctrl.c
> > ===================================================================
> > --- sys/dev/nand/nandsim_ctrl.c (revision 291978)
> > +++ sys/dev/nand/nandsim_ctrl.c (working copy)
> > @@ -388,9 +388,6 @@
> > rand = random();
> > if ((rand % 1000000) < chip->error_ratio) {
> > bit = rand % 8;
> > - if (*byte & (1 << bit))
> > - *byte &= ~(1 << bit);
> > - else
> > - *byte |= (1 << bit);
> > + *byte ^= (1 << bit);
> > }
> > }
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