# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1699834635 -3600
# Node ID 7a9f0b8c1418c7c3b6c61d1fc0f43b7f0fde2c6c
# Parent  bd3493979bfdc75b39d580b8fdf90e4c88235b98
Fixed control pin initialisation and unit sending.

diff -r bd3493979bfd -r 7a9f0b8c1418 pkg/devices/lib/spi/src/gpio.cc
--- a/pkg/devices/lib/spi/src/gpio.cc	Sun Nov 12 17:14:10 2023 +0100
+++ b/pkg/devices/lib/spi/src/gpio.cc	Mon Nov 13 01:17:15 2023 +0100
@@ -40,6 +40,7 @@
   _clock_device->setup(_clock_pin, Hw::Gpio_chip::Output, 1);
   _data_device->setup(_data_pin, Hw::Gpio_chip::Output, 0);
   _enable_device->setup(_enable_pin, Hw::Gpio_chip::Output, 1);
+  _control_device->setup(_control_pin, Hw::Gpio_chip::Output, 0);
 }
 
 Spi_gpio::Spi_gpio(uint64_t frequency,
@@ -101,7 +102,7 @@
       _clock_device->set(_clock_pin, 0);
       _data_device->set(_data_pin, data[byte] & mask ? 1 : 0);
 
-      if ((_control_device != NULL) && (dc != NULL))
+      if ((_control_device != NULL) && (_control_pin >= 0) && (dc != NULL))
         _control_device->set(_control_pin, dc[byte] ? 1 : 0);
 
       if (_frequency)
@@ -128,34 +129,53 @@
 uint32_t Spi_gpio::send_units(uint32_t bytes, const uint8_t data[],
                               uint8_t unit_size, uint8_t char_size)
 {
-  uint32_t count = bytes / unit_size;
-  int dc[count];
+  /* Obtain the data/command values for each unit. */
+
+  uint32_t chars = bytes / unit_size;
+  int dc[chars];
+
+  /* Obtain the actual character bytes to be sent. */
+
+  int char_unit_size = ((char_size ? char_size - 1 : 0) / 8) + 1;
+  uint8_t char_data[char_unit_size * chars];
 
   /* Traverse the byte sequence, extracting data/command bits for each unit. */
 
-  for (uint32_t offset = 0, unit = 0; offset < bytes; offset += unit_size, unit++)
+  for (uint32_t offset = 0, unit = 0, char_offset = 0; unit < chars;
+       offset += unit_size, unit++, char_offset += char_unit_size)
   {
+    /* Obtain the unit value. */
+
+    uint32_t value = 0;
+
+    for (uint8_t byte = 0; byte < unit_size; byte++)
+      value = (value << 8) | data[offset + byte];
+
     /* The unit size must be greater than the character size for data/command
        bits to be present. */
 
     if (unit_size * 8 <= char_size)
       dc[unit] = 0;
+
+    /* Extract the data/command level. */
+
     else
-    {
-      /* Obtain the unit value. */
-
-      uint32_t value = 0;
+      dc[unit] = value & (1 << char_size) ? 1 : 0;
 
-      for (uint8_t byte = 0; byte < unit_size; byte++)
-        value = (value << 8) | data[offset + byte];
+    /* Obtain the actual character data from the input data, discarding the most
+       significant bytes beyond the character and masking out any remaining
+       superfluous bits, thus obtaining a whole number of bytes. */
 
-      /* Extract the data/command level. */
+    value = value & ((1 << char_size) - 1);
 
-      dc[unit] = value & (1 << char_size) ? 1 : 0;
+    for (uint8_t byte = char_unit_size; byte != 0; byte--)
+    {
+      char_data[char_offset + byte - 1] = value & 0xff;
+      value >>= 8;
     }
   }
 
-  return send_dc(bytes, data, dc);
+  return send_dc(chars, char_data, dc);
 }