Re: [Outreachy kernel] [PATCH] staging: iio: Replace bit shifting with BIT macro

[Haneen Mohammed <hamohammed.sa@gmail.com>]

On Sun, Sep 17, 2017 at 08:56:40AM +0200, Julia Lawall wrote:
> 
> 
> On Sat, 16 Sep 2017, Haneen Mohammed wrote:
> 
> > This patch replace bit shifting on 0, 1, 2, and 3 with BIT(x) macro.
> > Issue resolved with the following Coccinelle script:
> >
> > @r1@
> > identifier x;
> > constant int g;
> > @@
> > (
> > 0<<\(x\|g\)
> > |
> > 1<<\(x\|g\)
> > |
> > 2<<\(x\|g\)
> > |
> > 3<<\(x\|g\)
> > )
> >
> > @script:python b@
> > g2 <<r1.g;
> > y;
> > @@
> >
> > coccinelle.y = int(g2) + 1
> >
> > @c@
> > constant int r1.g;
> > identifier b.y;
> > @@
> > (
> > -(1 << g)
> > +BIT(g)
> > |
> > -(0 << g)
> > + 0
> > |
> > -(2 << g)
> > +BIT(y)
> > |
> > -(3 << g)
> > +(BIT(y) | BIT(g))
> > )
> 
> Really good job on the semantic patch.
> 
> 

Thank you! I remember you helped me with it two years ago :)

> >
> > Signed-off-by: Haneen Mohammed <hamohammed.sa@gmail.com>
> > ---
> >  drivers/staging/iio/impedance-analyzer/ad5933.c | 38 ++++++++++++-------------
> >  1 file changed, 19 insertions(+), 19 deletions(-)
> >
> > diff --git a/drivers/staging/iio/impedance-analyzer/ad5933.c b/drivers/staging/iio/impedance-analyzer/ad5933.c
> > index 3d539ee..83d1a92 100644
> > --- a/drivers/staging/iio/impedance-analyzer/ad5933.c
> > +++ b/drivers/staging/iio/impedance-analyzer/ad5933.c
> > @@ -35,32 +35,32 @@
> >  #define AD5933_REG_IMAG_DATA		0x96	/* R, 2 bytes*/
> >
> >  /* AD5933_REG_CONTROL_HB Bits */
> > -#define AD5933_CTRL_INIT_START_FREQ	(0x1 << 4)
> > -#define AD5933_CTRL_START_SWEEP		(0x2 << 4)
> > -#define AD5933_CTRL_INC_FREQ		(0x3 << 4)
> > +#define AD5933_CTRL_INIT_START_FREQ	BIT(4)
> > +#define AD5933_CTRL_START_SWEEP		BIT(5)
> > +#define AD5933_CTRL_INC_FREQ		(BIT(5) | BIT(4))
> >  #define AD5933_CTRL_REPEAT_FREQ		(0x4 << 4)
> >  #define AD5933_CTRL_MEASURE_TEMP	(0x9 << 4)
> >  #define AD5933_CTRL_POWER_DOWN		(0xA << 4)
> >  #define AD5933_CTRL_STANDBY		(0xB << 4)
> 
> I'm not sure that this is a good idea.  Its more confusing than helpful to
> have the different styles mixed up.
> 
> 

I see. I wasn't sure how to convert the others so I left them.
I'll remove the bit macro from #define then.

Thank you!
Haneen

> > -#define AD5933_CTRL_RANGE_2000mVpp	(0x0 << 1)
> > -#define AD5933_CTRL_RANGE_200mVpp	(0x1 << 1)
> > -#define AD5933_CTRL_RANGE_400mVpp	(0x2 << 1)
> > -#define AD5933_CTRL_RANGE_1000mVpp	(0x3 << 1)
> > +#define AD5933_CTRL_RANGE_2000mVpp	0
> > +#define AD5933_CTRL_RANGE_200mVpp	BIT(1)
> > +#define AD5933_CTRL_RANGE_400mVpp	BIT(2)
> > +#define AD5933_CTRL_RANGE_1000mVpp	(BIT(2) | BIT(1))
> >  #define AD5933_CTRL_RANGE(x)		((x) << 1)
> >
> > -#define AD5933_CTRL_PGA_GAIN_1		(0x1 << 0)
> > -#define AD5933_CTRL_PGA_GAIN_5		(0x0 << 0)
> > +#define AD5933_CTRL_PGA_GAIN_1		BIT(0)
> > +#define AD5933_CTRL_PGA_GAIN_5		0
> 
> Again, this mixes styles.  Even though 0 << 0 is pretty silly as
> computation, it lines up well with what is above.
> 
> >  /* AD5933_REG_CONTROL_LB Bits */
> > -#define AD5933_CTRL_RESET		(0x1 << 4)
> > -#define AD5933_CTRL_INT_SYSCLK		(0x0 << 3)
> > -#define AD5933_CTRL_EXT_SYSCLK		(0x1 << 3)
> > +#define AD5933_CTRL_RESET		BIT(4)
> > +#define AD5933_CTRL_INT_SYSCLK		0
> > +#define AD5933_CTRL_EXT_SYSCLK		BIT(3)
> 
> Likewise.
> 
> >  /* AD5933_REG_STATUS Bits */
> > -#define AD5933_STAT_TEMP_VALID		(0x1 << 0)
> > -#define AD5933_STAT_DATA_VALID		(0x1 << 1)
> > -#define AD5933_STAT_SWEEP_DONE		(0x1 << 2)
> > +#define AD5933_STAT_TEMP_VALID		BIT(0)
> > +#define AD5933_STAT_DATA_VALID		BIT(1)
> > +#define AD5933_STAT_SWEEP_DONE		BIT(2)
> >
> >  /* I2C Block Commands */
> >  #define AD5933_I2C_BLOCK_WRITE		0xA0
> > @@ -229,7 +229,7 @@ static int ad5933_set_freq(struct ad5933_state *st,
> >  		u8 d8[4];
> >  	} dat;
> >
> > -	freqreg = (u64) freq * (u64) (1 << 27);
> > +	freqreg = (u64)freq * (u64)BIT(27);
> >  	do_div(freqreg, st->mclk_hz / 4);
> >
> >  	switch (reg) {
> > @@ -318,7 +318,7 @@ static ssize_t ad5933_show_frequency(struct device *dev,
> >  	freqreg = be32_to_cpu(dat.d32) & 0xFFFFFF;
> >
> >  	freqreg = (u64)freqreg * (u64)(st->mclk_hz / 4);
> > -	do_div(freqreg, 1 << 27);
> > +	do_div(freqreg, BIT(27));
> >
> >  	return sprintf(buf, "%d\n", (int)freqreg);
> >  }
> > @@ -452,9 +452,9 @@ static ssize_t ad5933_store(struct device *dev,
> >
> >  		/* 2x, 4x handling, see datasheet */
> >  		if (val > 1022)
> > -			val = (val >> 2) | (3 << 9);
> > +			val = (val >> 2) | (BIT(10) | BIT(9));
> 
> This would be better without the parentheses on (BIT(10) | BIT(9)
> 
> julia
> 
> >  		else if (val > 511)
> > -			val = (val >> 1) | (1 << 9);
> > +			val = (val >> 1) | BIT(9);
> >
> >  		dat = cpu_to_be16(val);
> >  		ret = ad5933_i2c_write(st->client,
> > --
> > 2.7.4
> >
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