1 files changed, 173 insertions, 0 deletions
diff --git a/FamicomDumper/Core/Src/comm.c b/FamicomDumper/Core/Src/comm.c
new file mode 100644
index 0000000..aaf6698
--- /dev/null
+++ b/FamicomDumper/Core/Src/comm.c
@@ -0,0 +1,173 @@
+#include "comm.h"
+#include "crc.h"
+#include "usbd_cdc_if.h"
+
+uint8_t send_buffer[SEND_BUFFER_SIZE];
+volatile uint16_t send_buffer_pos = 0;
+static uint8_t comm_send_crc;     // CRC of outgoing packet with header
+static uint16_t comm_send_length; // size of outgoing data
+static uint16_t comm_send_pos;    // how many data sent by app
+
+volatile uint8_t recv_buffer[RECV_BUFFER_SIZE];
+static uint16_t comm_recv_pos; // how many bytes of packet received
+static uint8_t comm_recv_crc;
+static uint8_t comm_recv_error;
+volatile uint8_t comm_recv_command;
+volatile uint16_t comm_recv_length;
+volatile uint8_t comm_recv_done;
+
+extern DMA_HandleTypeDef hdma_memtomem_dma1_channel1;
+extern volatile uint8_t dma_done;
+
+static uint8_t comm_flush(void)
+{
+  uint32_t start_time = HAL_GetTick();
+  uint8_t res;
+  do
+  {
+    if (HAL_GetTick() >= start_time + SEND_TIMEOUT) // timeout
+    {
+      comm_init();
+      return 0;
+    }
+    res = CDC_Transmit_FS((uint8_t*) send_buffer, send_buffer_pos);
+  } while (res != USBD_OK);
+  send_buffer_pos = 0;
+  return 1;
+}
+
+static void comm_send_and_calc(uint8_t data)
+{
+  comm_send_crc = calc_crc8(comm_send_crc, data);
+  send_buffer[send_buffer_pos++] = data;
+}
+
+static uint8_t check_send_buffer()
+{
+  uint8_t ok = 1;
+  if (send_buffer_pos >= sizeof(send_buffer))
+  {
+    ok &= comm_flush();
+    if (!ok) return ok;
+  }
+  if (comm_send_pos >= comm_send_length)
+  {
+    send_buffer[send_buffer_pos++] = comm_send_crc;
+    ok &= comm_flush();
+  }
+  return ok;
+}
+
+uint8_t comm_start(uint8_t command, uint16_t length)
+{
+  comm_send_crc = 0;
+  send_buffer_pos = 0;
+  comm_send_pos = 0;
+  comm_send_and_calc('F');
+  comm_send_and_calc(command);
+  comm_send_and_calc(length & 0xff);
+  comm_send_and_calc((length >> 8) & 0xff);
+  comm_send_length = length;
+  return check_send_buffer();
+}
+
+uint8_t comm_send_byte(uint8_t data)
+{
+  comm_send_and_calc(data);
+  comm_send_pos++;
+  return check_send_buffer();
+}
+
+uint8_t comm_send(uint8_t *address, uint16_t length)
+{
+  while (length)
+  {
+    if (!comm_send_byte(*address))
+      return 0;
+    address++;
+    length--;
+  }
+  return 1;
+}
+
+void comm_proceed(uint8_t data)
+{
+  if (comm_recv_error && data != 'F')
+    return;
+  comm_recv_error = 0;
+  if (!comm_recv_pos)
+  {
+    comm_recv_crc = 0;
+    comm_recv_done = 0;
+  }
+  comm_recv_crc = calc_crc8(comm_recv_crc, data);
+  switch (comm_recv_pos)
+  {
+  case 0:
+    {
+      if (data != 'F')
+      {
+        comm_recv_error = 1;
+        comm_start(COMMAND_ERROR_INVALID, 0);
+      }
+    }
+    break;
+  case 1:
+    {
+      comm_recv_command = data;
+    }
+    break;
+  case 2:
+    {
+      comm_recv_length = data;
+    }
+    break;
+  case 3:
+    {
+      comm_recv_length |= (uint16_t) data << 8;
+    }
+    break;
+  default:
+    {
+      uint16_t pos = comm_recv_pos - 4;
+      if (pos >= sizeof(recv_buffer))
+      {
+        comm_recv_pos = 0;
+        comm_recv_error = 1;
+        comm_start(COMMAND_ERROR_OVERFLOW, 0);
+        return;
+      } else if (pos < comm_recv_length)
+      {
+        recv_buffer[pos] = data;
+      } else if (pos == comm_recv_length)
+      {
+        if (!comm_recv_crc)
+        {
+          comm_recv_done = 1;
+        } else
+        {
+          comm_recv_error = 1;
+          comm_start(COMMAND_ERROR_CRC, 0);
+        }
+        comm_recv_pos = 0;
+        return;
+      }
+    }
+    break;
+  }
+  comm_recv_pos++;
+}
+
+void comm_init()
+{
+  send_buffer_pos = 0;
+  comm_send_crc = 0;
+  comm_send_length = 0;
+  comm_send_pos = 0;
+  comm_recv_pos = 0;
+  comm_recv_crc = 0;
+  comm_recv_error = 0;
+  comm_recv_command = 0;
+  comm_recv_length = 0;
+  comm_recv_done = 0;
+}