Merge pull request #101 from ACascarino/enhancement/ap316_16b_data

hotfix: add subst. in I2S doc, move decl. in tests

doc/programming_guide/reference/i2s/i2s_common.rst

@@ -7,9 +7,9 @@
 ===============
 
 The macro I2S_DATA_WIDTH may be set as a compile flag (e.g. 
--DI2S_DATA_WIDTH=16) to alter the number of bits per word for both the I2S 
-Master and I2S Slave components; this defaults to 32 bits per word. This 
-value may be set to any value between 1 and 32. Correct operation of the I2S 
+-DI2S_DATA_WIDTH=16) to alter the number of bits per word for both the |I2S| 
+Master and |I2S| Slave components; this defaults to 32 bits per word. This 
+value may be set to any value between 1 and 32. Correct operation of the |I2S| 
 components has only currently been verified at 16 and 32 bits per word.
 
 The following structures and functions are used by an |I2S| master or slave instance.

test/lib_i2s/i2s_slave_checker.py

@@ -99,7 +99,6 @@ def run(self):
                 f"CONFIG: bclk:{bclk_frequency} in:{num_ins} out:{num_outs} data_bits: {data_bits} i2s_justified:{is_i2s_justified}"
             )
             clock_half_period = float(ONE_SECOND_FS) / float(2 * bclk_frequency)
-            data_bit_mask = int("1" * data_bits, base=2)
 
             if self._invert_bclk:
                 bclk0 = 1
@@ -214,6 +213,8 @@ def run(self):
                         time = self.wait_until_ret(
                             time + clock_half_period - din_sample_offset
                         )
+
+                data_bit_mask = int("1" * data_bits, base=2)
 
                 for p in range(0, num_outs):
                     if (data_bit_mask & rx_data[p * 2][frame_count]) != rx_word[p]: