Re: [PATCH v4 6/7] IIO: add STM32 timer trigger driver

Daniel Thompson <daniel.thompson@xxxxxxxxxx> · Wed, 7 Dec 2016 12:01:52 +0000

On 07/12/16 11:00, Benjamin Gaignard wrote:
2016-12-07 11:50 GMT+01:00 Lee Jones <lee.jones@xxxxxxxxxx>:
On Tue, 06 Dec 2016, Benjamin Gaignard wrote:

[snip]
+
+static const char * const triggers0[] = {
+     TIM1_TRGO, TIM1_CH1, TIM1_CH2, TIM1_CH3, TIM1_CH4, NULL,
+};
+
+static const char * const triggers1[] = {
+     TIM2_TRGO, TIM2_CH1, TIM2_CH2, TIM2_CH3, TIM2_CH4, NULL,
+};
+
+static const char * const triggers2[] = {
+     TIM3_TRGO, TIM3_CH1, TIM3_CH2, TIM3_CH3, TIM3_CH4, NULL,
+};
+
+static const char * const triggers3[] = {
+     TIM4_TRGO, TIM4_CH1, TIM4_CH2, TIM4_CH3, TIM4_CH4, NULL,
+};
+
+static const char * const triggers4[] = {
+     TIM5_TRGO, TIM5_CH1, TIM5_CH2, TIM5_CH3, TIM5_CH4, NULL,
+};
+
+static const char * const triggers5[] = {
+     TIM6_TRGO, NULL,
+};
+
+static const char * const triggers6[] = {
+     TIM7_TRGO, NULL,
+};
+
+static const char * const triggers7[] = {
+     TIM8_TRGO, TIM8_CH1, TIM8_CH2, TIM8_CH3, TIM8_CH4, NULL,
+};
+
+static const char * const triggers8[] = {
+     TIM9_TRGO, TIM9_CH1, TIM9_CH2, NULL,
+};
+
+static const char * const triggers9[] = {
+     TIM12_TRGO, TIM12_CH1, TIM12_CH2, NULL,
+};
+
+static const void *triggers_table[] = {
+     triggers0,
+     triggers1,
+     triggers2,
+     triggers3,
+     triggers4,
+     triggers5,
+     triggers6,
+     triggers7,
+     triggers8,
+     triggers9,
+};

What about:

static const char * const triggers[][] = {
        { TIM1_TRGO, TIM1_CH1, TIM1_CH2, TIM1_CH3, TIM1_CH4, NULL },
        { TIM2_TRGO, TIM2_CH1, TIM2_CH2, TIM2_CH3, TIM2_CH4, NULL },
        { TIM3_TRGO, TIM3_CH1, TIM3_CH2, TIM3_CH3, TIM3_CH4, NULL },
        { TIM4_TRGO, TIM4_CH1, TIM4_CH2, TIM4_CH3, TIM4_CH4, NULL },
        { TIM5_TRGO, TIM5_CH1, TIM5_CH2, TIM5_CH3, TIM5_CH4, NULL },
        { TIM6_TRGO, NULL },
        { TIM7_TRGO, NULL },
        { TIM8_TRGO, TIM8_CH1, TIM8_CH2, TIM8_CH3, TIM8_CH4, NULL },
        { TIM9_TRGO, TIM9_CH1, TIM9_CH2, NULL },
        { TIM12_TRGO, TIM12_CH1, TIM12_CH2, NULL }
};

I can't because the second dimension of the array isn't fix.
I could have between 2 and 6 elements per row... to create a dual dimension
array I would have to add NULL entries like that:

#define MAX_TRIGGERS 6

static const void *triggers_table[][MAX_TRIGGERS] = {
{ TIM1_TRGO, TIM1_CH1, TIM1_CH2, TIM1_CH3, TIM1_CH4, NULL,},
{ TIM2_TRGO, TIM2_CH1, TIM2_CH2, TIM2_CH3, TIM2_CH4, NULL,},
{ TIM3_TRGO, TIM3_CH1, TIM3_CH2, TIM3_CH3, TIM3_CH4, NULL,},
{ TIM4_TRGO, TIM4_CH1, TIM4_CH2, TIM4_CH3, TIM4_CH4, NULL,},
{ TIM5_TRGO, TIM5_CH1, TIM5_CH2, TIM5_CH3, TIM5_CH4, NULL,},
{ TIM6_TRGO, NULL,     NULL,     NULL,     NULL,     NULL,},
{ TIM7_TRGO, NULL,     NULL,     NULL,     NULL,     NULL,},
{ TIM8_TRGO, TIM8_CH1, TIM8_CH2, TIM8_CH3, TIM8_CH4, NULL,},
{ TIM9_TRGO, TIM9_CH1, TIM9_CH2, NULL,     NULL,     NULL,},
{ TIM12_TRGO, TIM12_CH1, TIM12_CH2, NULL,  NULL,     NULL,},
};

It was just an idea, not a tested implementation.

I don't understand why you have to pad with NULLs, but either way, it
looks much better than before and saves lots of lines of code.

I have tested it this morning and it works fine so I will include it in v5.
I use NULL as limit when iterate in the table and for table padding too.

If the initializer is shorter than the array then the array will be 
implicitly zero/NULL padded. I don't think there is any need to type out 
all the NULLs (not even at -Wall).

Daniel.

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