aio: add calls for changing bit value of the read

Signed-off-by: Thomas Ingleby <thomas.c.ingleby@intel.com>

api/mraa/aio.h

@@ -74,6 +74,24 @@ uint16_t mraa_aio_read(mraa_aio_context dev);
  */
 mraa_result_t mraa_aio_close(mraa_aio_context dev);
 
+/**
+ * Set the bit value which mraa will shift the raw reading
+ * from the ADC to. I.e. 10bits
+ * @param dev the analog input context
+ * @param bits the bits the return from read should be i.e 10
+ *
+ * @return mraa result type
+ */
+mraa_result_t mraa_aio_set_bit(mraa_aio_context dev, int bits);
+
+/**
+ * Gets the bit value mraa is shifting the analog read to.
+ * @param dev the analog input context
+ *
+ * @return bit value mraa is set return from the read function
+ */
+int mraa_aio_get_bit(mraa_aio_context dev);
+
 #ifdef __cplusplus
 }
 #endif

api/mraa/aio.hpp

@@ -62,6 +62,24 @@ class Aio {
             // Use basic types to make swig code generation simpler
             return (int) mraa_aio_read(m_aio);
         }
+        /**
+         * Set the bit value which mraa will shift the raw reading
+         * from the ADC to. I.e. 10bits
+         * @param bits the bits the return from read should be i.e 10
+         * @return mraa result type
+         */
+        mraa_result_t set_bit(int bits) {
+            return mraa_aio_set_bit(m_aio, bits);
+        }
+        /**
+         * Gets the bit value mraa is shifting the analog read to.
+         *
+         * @return bit value mraa is set return from the read function
+         */
+        int get_bit() {
+            return mraa_aio_get_bit(m_aio);
+        }
+
     private:
         mraa_aio_context m_aio;
 };

include/mraa_internal_types.h

@@ -76,4 +76,5 @@ struct _pwm {
 struct _aio {
     unsigned int channel; /**< the channel as on board and ADC module */
     int adc_in_fp; /**< File Pointer to raw sysfs */
+    int value_bit; /**< 10 bits by default. Can be increased if board */
 };

src/aio/aio.c

@@ -29,8 +29,9 @@
 #include "aio.h"
 #include "mraa_internal.h"
 
+#define DEFAULT_BITS 10
+
 static int raw_bits;
-static int sup_bits;
 
 static mraa_result_t aio_get_valid_fp(mraa_aio_context dev)
 {
@@ -92,6 +93,7 @@ mraa_aio_context mraa_aio_init(unsigned int aio_channel)
         return NULL;
     }
     dev->channel = checked_pin;
+    dev->value_bit = DEFAULT_BITS;
 
     //Open valid  analog input file and get the pointer.
     if (MRAA_SUCCESS != aio_get_valid_fp(dev)) {
@@ -99,7 +101,6 @@ mraa_aio_context mraa_aio_init(unsigned int aio_channel)
         return NULL;
     }
     raw_bits = mraa_adc_raw_bits();
-    sup_bits = mraa_adc_supported_bits();
 
     if (advance_func->aio_init_post != NULL) {
         mraa_result_t ret = advance_func->aio_init_post(dev);
@@ -146,13 +147,13 @@ uint16_t mraa_aio_read(mraa_aio_context dev)
         fprintf(stderr, "errno was set\n");
     }
 
+    if (dev->value_bit != raw_bits) {
         /* Adjust the raw analog input reading to supported resolution value*/
-    if (raw_bits != sup_bits) {
+        if (raw_bits > dev->value_bit) {
-        if (raw_bits > sup_bits) {
+            shifter_value = raw_bits - dev->value_bit;
-            shifter_value = raw_bits - sup_bits;
             analog_value =  analog_value >> shifter_value;
         } else {
-            shifter_value = sup_bits - raw_bits;
+            shifter_value = dev->value_bit - raw_bits;
             analog_value = analog_value << shifter_value;
         }
     }
@@ -173,3 +174,40 @@ mraa_result_t mraa_aio_close(mraa_aio_context dev)
 
     return(MRAA_SUCCESS);
 }
+
+/** Set the bits value from read.
+ *
+ * @param dev the analog input context
+ * @param bits the bits the return from read should be i.e 10
+ *
+ * @return mraa result type
+ */
+mraa_result_t mraa_aio_set_bit(mraa_aio_context dev, int bits)
+{
+    if (dev == NULL) {
+        fprintf(stderr, "AIO Device not valid\n");
+        return MRAA_ERROR_INVALID_RESOURCE;
+    }
+    if (bits < 1) {
+        fprintf(stderr, "AIO Device not valid\n");
+        // Error Message Here. find with grep fprintf
+        return MRAA_ERROR_INVALID_PARAMETER;
+    }
+    dev->value_bit = bits;
+    return MRAA_SUCCESS;
+}
+
+/**
+ * Gets the bit value mraa is shifting the analog read to.
+ * @param dev the analog input context
+ *
+ * @return bit value mraa is set return from the read function
+ */
+int mraa_aio_get_bit(mraa_aio_context dev)
+{
+    if (dev == NULL) {
+        fprintf(stderr, "AIO Device not valid\n");
+        return 0;
+    }
+    return dev->value_bit;
+}