diff --git a/imask.h b/imask.h
new file mode 100644
index 0000000..620dcc0
--- /dev/null
+++ b/imask.h
@@ -0,0 +1,20 @@
+#pragma once
+
+#include <cstdint>
+
+inline void set_imask(uint32_t imask)
+{
+  uint32_t sr;
+
+  asm volatile ("stc sr,%0"
+		: "=r" (sr)
+		:
+		);
+
+  sr = (sr & ~0xf0) | (imask << 4);
+
+  asm volatile ("ldc %0,sr"
+		:
+		: "r" (sr)
+		);
+}
diff --git a/main.cpp b/main.cpp
index 7071c90..a2af41a 100644
--- a/main.cpp
+++ b/main.cpp
@@ -11,6 +11,8 @@
 #include "systembus.h"
 #include "maple/maple.h"
 #include "maple/maple_bits.h"
+#include "maple/maple_bus_commands.h"
+#include "maple/maple_bus_ft0.h"
 
 #include "holly/texture_memory_alloc.h"
 
@@ -47,6 +49,10 @@ inline void serial_char(const char c)
   // wait for transmit fifo to become empty
   while ((sh7091.SCIF.SCFSR2 & SCFSR2__TDFE) == 0);
 
+  for (int i = 0; i < 100000; i++) {
+    asm volatile ("nop;");
+  }
+
   sh7091.SCIF.SCFTDR2 = static_cast<uint8_t>(c);
 }
 
@@ -60,14 +66,16 @@ void serial_string(const char * s)
 /* must be aligned to 32-bytes for DMA transfer */
 // the aligned(32) attribute does not actually align to 32 bytes; gcc is the best compiler.
 // `+ 32` to allow for repositioning _scene to an actual 32-byte alignment.
-uint32_t __attribute__((aligned(32))) _scene[((32 * 6) + 32) / 4];
+// __attribute__((aligned(32)))
+uint32_t _scene[((32 * 6) + 32) / 4];
 
-uint32_t * align_32byte(uint32_t * mem)
+template <typename T>
+T * align_32byte(T * mem)
 {
-  return reinterpret_cast<uint32_t *>(((reinterpret_cast<uint32_t>(_scene) + 31) & ~31));
+  return reinterpret_cast<T *>((((reinterpret_cast<uint32_t>(mem) + 31) & ~31)));
 }
 
-void serial_int(const uint32_t n)
+void serial_int32(const uint32_t n)
 {
   char num_buf[9];
   string::hex<char>(num_buf, 8, n);
@@ -77,19 +85,52 @@ void serial_int(const uint32_t n)
   serial_string("\n");
 }
 
-void maple_test()
+void serial_int8(const uint8_t n)
+{
+  char num_buf[3];
+  string::hex<char>(num_buf, 2, n);
+  num_buf[2] = 0;
+  serial_string("0x");
+  serial_string(num_buf);
+  serial_string("\n");
+}
+
+uint32_t _receive_address[(32 + 32) / 4] = {0};
+uint32_t _command_buf[(32 + 32) / 4] = {0};
+
+bool maple_test()
 {
-  uint32_t _command_buf[(32 + 32) / 4];
-  uint32_t _receive_address[(32 + 32) / 4];
   uint32_t * command_buf = align_32byte(_command_buf);
   uint32_t * receive_address = align_32byte(_receive_address);
+  if ((((uint32_t)command_buf) & 31) != 0) serial_string("misaligned\n");
+  if ((((uint32_t)receive_address) & 31) != 0) serial_string("misaligned\n");
+
+  for (int i = 0; i < (32 / 4); i++) {
+    command_buf[i] = 0;
+  }
+
+  for (int i = 0; i < (32 / 4); i++) {
+    receive_address[i] = 0;
+  }
+
+  v_sync_out();
+
+  //maple_init_device_request(command_buf, receive_address);
+  maple_init_get_condition(command_buf, receive_address);
 
-  maple_init_host_command(command_buf, receive_address);
   maple_dma_start(command_buf);
 
-  for (int i = 0; i < 32; i++) {
-    serial_int(receive_address[i]);
+  v_sync_in();
+
+  /*
+  for (int i = 0; i < (4 + 4 + 8); i++) {
+    serial_int8(reinterpret_cast<volatile uint8_t *>(receive_address)[i]);
   }
+  */
+
+  // the data format for a FT0 (controller) data read
+  auto data_format = reinterpret_cast<volatile data_transfer::data_fields<ft0::data_transfer::data_format> *>(&receive_address[1]);
+  return !(data_format->data.digital_button & ft0::data_transfer::digital_button::a);
 }
 
 extern "C"
@@ -110,8 +151,7 @@ void main()
 
   v_sync_in();
 
-  maple_test();
-
+  /*
   volatile uint16_t * framebuffer = reinterpret_cast<volatile uint16_t *>(&texture_memory[0]);
   for (int y = 0; y < 480; y++) {
     for (int x = 0; x < 640; x++) {
@@ -120,7 +160,9 @@ void main()
       framebuffer[y * 640 + x] = ((rgb.r >> 3) << 11) | ((rgb.g >> 2) << 5) | ((rgb.b >> 3) << 0);
     }
   }
+  */
 
+  /*
   volatile texture_memory_alloc * mem = reinterpret_cast<volatile texture_memory_alloc *>(0xa400'0000);
 
   volatile uint8_t * macaw = reinterpret_cast<volatile uint8_t *>(&_binary_macaw_data_start);
@@ -133,6 +175,7 @@ void main()
     uint16_t rgb565 = ((r / 8) << 11) | ((g / 4) << 5) | ((b / 8) << 0);
     mem->texture[px] = rgb565;
   }
+  */
 
   holly.SOFTRESET = softreset::pipeline_soft_reset
 		  | softreset::ta_soft_reset;
@@ -156,17 +199,22 @@ void main()
   }
 
   int frame = 0;
+  bool a_pressed = 0;
+  uint32_t color;
 
   while (true) {
     v_sync_out();
     v_sync_in();
 
     ta_polygon_converter_init();
-    uint32_t ta_parameter_size = scene_transform(scene);
+    if (a_pressed) { color = 0xffffffff; } else { color = 0xffff7f00; }
+    uint32_t ta_parameter_size = scene_transform_quad(scene, color);
     ta_polygon_converter_transfer(scene, ta_parameter_size);
     ta_wait_opaque_list();
     core_start_render(frame);
 
+    a_pressed = maple_test();
+
     frame = !frame;
   }
 }
diff --git a/maple/maple.cpp b/maple/maple.cpp
index 022d732..7bf3259 100644
--- a/maple/maple.cpp
+++ b/maple/maple.cpp
@@ -24,20 +24,41 @@ struct maple_host_command {
   } bus_data;
 };
 
-void maple_init_host_command(uint32_t * buf, uint32_t * receive_address)
+void maple_init_host_command(uint32_t * buf, uint32_t * receive_address, uint8_t command_code, uint8_t data_size)
 {
-  auto host_command = reinterpret_cast<maple_host_command<device_request::data_fields> *>(buf);
+  // this function does not care about the template instantiation of
+  // maple_host_command--data_fields is not manipulated here.
+  auto host_command = reinterpret_cast<maple_host_command<uint32_t> *>(buf);
 
   host_command->host_instruction = host_instruction::end_flag
                                  | host_instruction::port_select::a
-                                 | host_instruction::transfer_length(0); // 4 bytes
+                                 | host_instruction::transfer_length((data_size / 4));
 
-  host_command->receive_data_storage_address = reinterpret_cast<uint32_t>(receive_address);
+  host_command->receive_data_storage_address = reinterpret_cast<uint32_t>(receive_address) & 0x1fff'ffff;
 
-  host_command->bus_data.command_code = device_request::command_code;
+  host_command->bus_data.command_code = command_code;
   host_command->bus_data.destination_ap = ap::de::device | ap::port_select::a;
   host_command->bus_data.source_ap = ap::port_select::a;
-  host_command->bus_data.data_size = 0;
+  host_command->bus_data.data_size = data_size / 4;
+}
+
+void maple_init_device_request(uint32_t * buf, uint32_t * receive_address)
+{
+  maple_init_host_command(buf, receive_address, device_request::command_code, (sizeof (struct device_request::data_fields)));
+}
+
+void maple_init_get_condition(uint32_t * buf, uint32_t * receive_address)
+{
+  maple_init_host_command(buf, receive_address, get_condition::command_code, (sizeof (struct get_condition::data_fields)));
+
+  auto host_command = reinterpret_cast<maple_host_command<get_condition::data_fields> *>(buf);
+
+  auto& function_type = host_command->bus_data.data_fields.function_type;
+  // controller function type
+  function_type[0] = 0x00;
+  function_type[1] = 0x00;
+  function_type[2] = 0x00;
+  function_type[3] = 0x01;
 }
 
 void maple_dma_start(uint32_t * command_buf)
@@ -52,29 +73,28 @@ void maple_dma_start(uint32_t * command_buf)
   // disable maple-DMA
   maple_if.MDEN = mden::dma_enable::abort;
 
-  volatile uint32_t _dummy = maple_if.MDST;
-  (void)_dummy;
+  while (mdst::start_status::status(maple_if.MDST) != 0);
 
   // 20nsec * 0xc350 = 1ms
   constexpr uint32_t one_msec = 0xc350;
   maple_if.MSYS = msys::time_out_counter(one_msec)
                 | msys::sending_rate::_2M;
 
-  maple_if.MDTSEL = mdtsel::trigger_select::software_initiation;
-
   /* top address: the first/lowest address
      bottom address: the last/highest address */
   maple_if.MDAPRO = mdapro::security_code
 		  | mdapro::top_address(0x00)
 		  | mdapro::bottom_address(0x7f);
 
+  maple_if.MDTSEL = mdtsel::trigger_select::software_initiation;
+
   maple_if.MDSTAR = mdstar::table_address(reinterpret_cast<uint32_t>(command_buf));
 
   maple_if.MDEN = mden::dma_enable::enable;
   maple_if.MDST = mdst::start_status::start;
 
   // wait for completion
+  //while (mdst::start_status::status(maple_if.MDST) != 0);
   while ((system.ISTNRM & ISTNRM__END_OF_DMA_MAPLE_DMA) == 0);
-
   system.ISTNRM = ISTNRM__END_OF_DMA_MAPLE_DMA;
 }
diff --git a/maple/maple.h b/maple/maple.h
index a0cd7d4..f756759 100644
--- a/maple/maple.h
+++ b/maple/maple.h
@@ -3,4 +3,6 @@
 #include <cstdint>
 
 void maple_init_host_command(uint32_t * buf, uint32_t * receive_address);
+void maple_init_device_request(uint32_t * buf, uint32_t * receive_address);
+void maple_init_get_condition(uint32_t * buf, uint32_t * receive_address);
 void maple_dma_start(uint32_t * command_buf);
diff --git a/maple/maple_bus_commands.h b/maple/maple_bus_commands.h
index 259b86c..68b90fc 100644
--- a/maple/maple_bus_commands.h
+++ b/maple/maple_bus_commands.h
@@ -47,7 +47,7 @@ namespace device_status {
 namespace device_all_status {
   constexpr uint32_t command_code = 0x6;
   
-  template <int N>
+  template <typename T>
   struct data_fields {
     uint8_t device_id[16];
     uint8_t destination_code[1];
@@ -56,10 +56,10 @@ namespace device_all_status {
     uint8_t license[60];
     uint8_t low_consumption_standby_current[2];
     uint8_t maximum_current_consumption[2];
-    uint8_t free_device_status[N];
+    T free_device_status;
   };
   
-  static_assert((sizeof (struct data_fields<0>)) == 112);
+  static_assert((sizeof (struct data_fields<char[0]>)) == 112);
 }
 
 namespace device_reply {
@@ -72,12 +72,13 @@ namespace device_reply {
 namespace data_transfer {
   constexpr uint32_t command_code = 0x8;
   
-  template <int N>
+  template <typename T>
   struct data_fields {
-    uint8_t data[N];
+    uint8_t function_type[4];
+    T data;
   };
   
-  static_assert((sizeof (struct data_fields<0>)) == 0);
+  static_assert((sizeof (struct data_fields<char[0]>)) == 4);
 }
 
 namespace get_condition {
@@ -117,16 +118,16 @@ namespace block_read {
 namespace block_write {
   constexpr uint32_t command_code = 0xc;
   
-  template <int N>
+  template <typename T>
   struct data_fields {
     uint8_t function_type[4];
     uint8_t pt[1];
     uint8_t phase[1];
     uint8_t block_no[2];
-    uint8_t written_data[N];
+    T written_data;
   };
   
-  static_assert((sizeof (struct data_fields<0>)) == 8);
+  static_assert((sizeof (struct data_fields<char[0]>)) == 8);
 }
 
 namespace get_last_error {
@@ -145,37 +146,37 @@ namespace get_last_error {
 namespace set_condition {
   constexpr uint32_t command_code = 0xe;
   
-  template <int N>
+  template <typename T>
   struct data_fields {
     uint8_t function_type[4];
-    uint8_t write_in_data[N];
+    T write_in_data;
   };
   
-  static_assert((sizeof (struct data_fields<0>)) == 4);
+  static_assert((sizeof (struct data_fields<char[0]>)) == 4);
 }
 
 namespace ft4_control {
   constexpr uint32_t command_code = 0xf;
   
-  template <int N>
+  template <typename T>
   struct data_fields {
     uint8_t function_type[4];
-    uint8_t ft4_data[N];
+    T ft4_data;
   };
   
-  static_assert((sizeof (struct data_fields<0>)) == 4);
+  static_assert((sizeof (struct data_fields<char[0]>)) == 4);
 }
 
 namespace ar_control {
   constexpr uint32_t command_code = 0x10;
   
-  template <int N>
+  template <typename T>
   struct data_fields {
     uint8_t function_type[4];
-    uint8_t data[N];
+    T data;
   };
   
-  static_assert((sizeof (struct data_fields<0>)) == 4);
+  static_assert((sizeof (struct data_fields<char[0]>)) == 4);
 }
 
 namespace function_type_unknown {
diff --git a/maple/maple_bus_ft0.h b/maple/maple_bus_ft0.h
new file mode 100644
index 0000000..3c37d7a
--- /dev/null
+++ b/maple/maple_bus_ft0.h
@@ -0,0 +1,34 @@
+namespace ft0 {
+  namespace data_transfer {
+    namespace digital_button {
+      constexpr uint32_t ra = 1 << 7;
+      constexpr uint32_t la = 1 << 6;
+      constexpr uint32_t da = 1 << 5;
+      constexpr uint32_t ua = 1 << 4;
+      constexpr uint32_t start = 1 << 3;
+      constexpr uint32_t a = 1 << 2;
+      constexpr uint32_t b = 1 << 1;
+      constexpr uint32_t c = 1 << 0;
+      constexpr uint32_t rb = 1 << 15;
+      constexpr uint32_t lb = 1 << 14;
+      constexpr uint32_t db = 1 << 13;
+      constexpr uint32_t ub = 1 << 12;
+      constexpr uint32_t d = 1 << 11;
+      constexpr uint32_t x = 1 << 10;
+      constexpr uint32_t y = 1 << 9;
+      constexpr uint32_t z = 1 << 8;
+    }
+    
+    struct data_format {
+      uint16_t digital_button;
+      uint8_t analog_axis_1;
+      uint8_t analog_axis_2;
+      uint8_t analog_axis_3;
+      uint8_t analog_axis_4;
+      uint8_t analog_axis_5;
+      uint8_t analog_axis_6;
+    };
+    static_assert((sizeof (struct data_format)) == 8);
+  }
+}
+
diff --git a/maple_bus_commands.h b/maple_bus_commands.h
deleted file mode 100644
index 18c41cc..0000000
--- a/maple_bus_commands.h
+++ /dev/null
@@ -1,225 +0,0 @@
-#include <stdint.h>
-#include <stddef.h>
-
-#include "type.h"
-
-namespace device_request {
-  constexpr uint32_t command_code = 0x1;
-  struct data_fields {
-  };
-}
-
-namespace all_status_request {
-  constexpr uint32_t command_code = 0x2;
-  struct data_fields {
-  };
-}
-
-namespace device_reset {
-  constexpr uint32_t command_code = 0x3;
-  struct data_fields {
-  };
-}
-
-namespace device_kill {
-  constexpr uint32_t command_code = 0x4;
-  struct data_fields {
-  };
-}
-
-namespace device_status {
-  constexpr uint32_t command_code = 0x5;
-  struct data_fields {
-
-    uint8_t device_id[16];
-    uint8_t destination_code[1];
-    uint8_t connection_direction[1];
-    uint8_t product_name[30];
-    uint8_t license[60];
-    uint8_t low_consumption_standby_current[2];
-    uint8_t maximum_current_consumption[2];
-  };
-
-  static_assert((sizeof (struct data_fields)) == 112);
-}
-
-namespace device_all_status {
-  constexpr uint32_t command_code = 0x6;
-  struct data_fields {
-
-    template <int N>
-    uint8_t device_id[16];
-    uint8_t destination_code[1];
-    uint8_t connection_direction[1];
-    uint8_t product_name[30];
-    uint8_t license[60];
-    uint8_t low_consumption_standby_current[2];
-    uint8_t maximum_current_consumption[2];
-    uint8_t free_device_status[N];
-  };
-
-  static_assert((sizeof (struct data_fields<0>)) == 112);
-}
-
-namespace device_reply {
-  constexpr uint32_t command_code = 0x7;
-  struct data_fields {
-  };
-}
-
-namespace data_transfer {
-  constexpr uint32_t command_code = 0x8;
-  struct data_fields {
-
-    template <int N>
-    uint8_t data[N];
-  };
-
-  static_assert((sizeof (struct data_fields<0>)) == 0);
-}
-
-namespace get_condition {
-  constexpr uint32_t command_code = 0x9;
-  struct data_fields {
-
-    uint8_t function_type[4];
-  };
-
-  static_assert((sizeof (struct data_fields)) == 4);
-}
-
-namespace get_media_info {
-  constexpr uint32_t command_code = 0xa;
-  struct data_fields {
-
-    uint8_t function_type[4];
-    uint8_t pt[4];
-  };
-
-  static_assert((sizeof (struct data_fields)) == 8);
-}
-
-namespace block_read {
-  constexpr uint32_t command_code = 0xb;
-  struct data_fields {
-
-    uint8_t function_type[4];
-    uint8_t pt[1];
-    uint8_t phase[1];
-    uint8_t block_no[2];
-  };
-
-  static_assert((sizeof (struct data_fields)) == 8);
-}
-
-namespace block_write {
-  constexpr uint32_t command_code = 0xc;
-  struct data_fields {
-
-    template <int N>
-    uint8_t function_type[4];
-    uint8_t pt[1];
-    uint8_t phase[1];
-    uint8_t block_no[2];
-    uint8_t written_data[N];
-  };
-
-  static_assert((sizeof (struct data_fields<0>)) == 8);
-}
-
-namespace get_last_error {
-  constexpr uint32_t command_code = 0xd;
-  struct data_fields {
-
-    uint8_t function_type[4];
-    uint8_t pt[1];
-    uint8_t phase[1];
-    uint8_t block_no[2];
-  };
-
-  static_assert((sizeof (struct data_fields)) == 8);
-}
-
-namespace set_condition {
-  constexpr uint32_t command_code = 0xe;
-  struct data_fields {
-
-    template <int N>
-    uint8_t function_type[4];
-    uint8_t write_in_data[N];
-  };
-
-  static_assert((sizeof (struct data_fields<0>)) == 4);
-}
-
-namespace ft4_control {
-  constexpr uint32_t command_code = 0xf;
-  struct data_fields {
-
-    template <int N>
-    uint8_t function_type[4];
-    uint8_t ft4_data[N];
-  };
-
-  static_assert((sizeof (struct data_fields<0>)) == 4);
-}
-
-namespace ar_control {
-  constexpr uint32_t command_code = 0x10;
-  struct data_fields {
-
-    template <int N>
-    uint8_t function_type[4];
-    uint8_t data[N];
-  };
-
-  static_assert((sizeof (struct data_fields<0>)) == 4);
-}
-
-namespace function_type_unknown {
-  constexpr uint32_t command_code = 0xfe;
-  struct data_fields {
-  };
-}
-
-namespace command_unknown {
-  constexpr uint32_t command_code = 0xfd;
-  struct data_fields {
-  };
-}
-
-namespace transmit_again {
-  constexpr uint32_t command_code = 0xfc;
-  struct data_fields {
-  };
-}
-
-namespace file_error {
-  constexpr uint32_t command_code = 0xfb;
-  struct data_fields {
-
-    uint8_t function_error_code[4];
-  };
-
-  static_assert((sizeof (struct data_fields)) == 4);
-}
-
-namespace lcd_error {
-  constexpr uint32_t command_code = 0xfa;
-  struct data_fields {
-
-    uint8_t function_error_code[4];
-  };
-
-  static_assert((sizeof (struct data_fields)) == 4);
-}
-
-namespace ar_error {
-  constexpr uint32_t command_code = 0xf9;
-  struct data_fields {
-
-    uint8_t function_error_code[4];
-  };
-
-  static_assert((sizeof (struct data_fields)) == 4);
-}
diff --git a/regs/gen/maple_commands.py b/regs/gen/maple_commands.py
index 30dd322..6429bb1 100644
--- a/regs/gen/maple_commands.py
+++ b/regs/gen/maple_commands.py
@@ -27,7 +27,7 @@ def command_namespace(namespace: CommandNamespace,
 
         if variable is not None:
             assert variable.lower() == "n"
-            yield "template <int N>"
+            yield "template <typename T>"
 
         yield "struct data_fields {"
 
@@ -37,7 +37,7 @@ def command_namespace(namespace: CommandNamespace,
                 yield f"uint8_t {field_name}[{const}];"
             elif const == 0:
                 assert var == "n"
-                yield f"uint8_t {field_name}[{var.upper()}];"
+                yield f"T {field_name};"
             else:
                 yield f"uint8_t {field_name}[{const} + {var.upper()}];"
 
@@ -47,7 +47,7 @@ def command_namespace(namespace: CommandNamespace,
 
         if variable is not None:
             assert variable == "n"
-            yield f"static_assert((sizeof (struct data_fields<0>)) == {length});"
+            yield f"static_assert((sizeof (struct data_fields<char[0]>)) == {length});"
         else:
             yield f"static_assert((sizeof (struct data_fields)) == {length});"
 
diff --git a/regs/gen/maple_data_format.py b/regs/gen/maple_data_format.py
new file mode 100644
index 0000000..116c713
--- /dev/null
+++ b/regs/gen/maple_data_format.py
@@ -0,0 +1,124 @@
+import csv
+import sys
+from dataclasses import dataclass
+from collections import defaultdict
+
+from generate import renderer
+
+@dataclass
+class Field:
+    name: str
+    bits: list[str]
+
+@dataclass
+class Format:
+    name: str
+    fields: list[Field]
+    field_order: list[str]
+    size: int
+
+def read_input(filename):
+    with open(filename) as f:
+        reader = csv.reader(f, delimiter=",", quotechar='"')
+        rows = [
+            [s.strip() for s in row]
+            for row in reader
+        ]
+    return rows
+
+def parse_data_format(ix, rows):
+    if ix >= len(rows):
+        return None
+
+    while rows[ix][0] == "":
+        ix += 1
+        if ix >= len(rows):
+            return None
+
+    format_name, *header = rows[ix]
+    ix += 1
+    assert format_name != ""
+    assert header == ["7", "6", "5", "4", "3", "2", "1", "0"]
+
+    fields = defaultdict(list)
+    field_order = list()
+    size = 0
+    while ix < len(rows) and rows[ix][0] != "":
+        field_name, *_bits = rows[ix]
+        ix += 1
+        excess_bits = [b for b in _bits[8:] if b != ""]
+        assert excess_bits == []
+        bits = [b for b in _bits[:8] if b != ""]
+        assert len(bits) in {0, 8}, bits
+        fields[field_name].append(Field(field_name, list(bits)))
+        size += 1
+        if field_name not in field_order:
+            field_order.append(field_name)
+
+    return ix, Format(format_name, dict(fields), field_order, size)
+
+def parse(rows):
+    ix = 0
+    formats = []
+
+    while True:
+        ix_format = parse_data_format(ix, rows)
+        if ix_format is None:
+            break
+        ix, format = ix_format
+        formats.append(format)
+
+    assert len(formats) > 0
+    return formats
+
+bit_order = [7, 6, 5, 4, 3, 2, 1, 0]
+
+def render_format(format):
+    yield f"namespace {format.name} {{"
+    for field_name in format.field_order:
+        subfields = format.fields[field_name]
+        if not any(field.bits != [] for field in subfields):
+            continue
+
+        yield f"namespace {field_name} {{"
+        for ix, field in enumerate(subfields):
+            bit_offset = 8 * ix
+            if field.bits != []:
+                assert len(field.bits) == 8
+                for byte_ix, bit in zip(bit_order, field.bits):
+                    bit_ix = byte_ix + bit_offset
+                    yield f"constexpr uint32_t {bit.lower()} = 1 << {bit_ix};"
+        yield "}"
+        yield ""
+
+    yield f"struct data_format {{"
+
+    for field_name in format.field_order:
+        subfields = format.fields[field_name]
+        if len(subfields) == 1:
+            field, = subfields
+            yield f"uint8_t {field_name};"
+        elif len(subfields) == 2:
+            yield f"uint16_t {field_name};"
+        else:
+            assert False, len(subfields)
+
+    yield "};"
+    assert format.size % 4 == 0, format.size
+    yield f"static_assert((sizeof (struct data_format)) == {format.size});"
+    yield "}"
+
+def render_formats(name, formats):
+    yield f"namespace {name} {{"
+    for format in formats:
+        yield from render_format(format)
+    yield "}"
+
+if __name__ == "__main__":
+    rows = read_input(sys.argv[1])
+    name = sys.argv[1].split('.')[0].split('_')[-1]
+    assert len(name) == 3 or len(name) == 4
+    formats = parse(rows)
+    render, out = renderer()
+    render(render_formats(name, formats))
+    print(out.getvalue())
diff --git a/regs/maple_bus_commands.csv b/regs/maple_bus_commands.csv
index e3700de..a065431 100644
--- a/regs/maple_bus_commands.csv
+++ b/regs/maple_bus_commands.csv
@@ -26,7 +26,8 @@
 ,,,,,
 "device_reply","peripheral","0x07","0x00",,
 ,,,,,
-"data_transfer","peripheral","0x08","n/4","data","n"
+"data_transfer","peripheral","0x08","0x01+n/4","function_type",4
+"data_transfer",,,,"data","n"
 ,,,,,
 "get_condition","host","0x09","0x01","function_type",4
 ,,,,,
diff --git a/regs/maple_bus_commands.ods b/regs/maple_bus_commands.ods
index abd09bd..1b56cf8 100644
Binary files a/regs/maple_bus_commands.ods and b/regs/maple_bus_commands.ods differ
diff --git a/regs/maple_bus_ft0.csv b/regs/maple_bus_ft0.csv
new file mode 100644
index 0000000..a081908
--- /dev/null
+++ b/regs/maple_bus_ft0.csv
@@ -0,0 +1,9 @@
+"data_transfer",7,6,5,4,3,2,1,0
+"digital_button","Ra","La","Da","Ua","Start","A","B","C"
+"digital_button","Rb","Lb","Db","Ub","D","X","Y","Z"
+"analog_axis_1",,,,,,,,
+"analog_axis_2",,,,,,,,
+"analog_axis_3",,,,,,,,
+"analog_axis_4",,,,,,,,
+"analog_axis_5",,,,,,,,
+"analog_axis_6",,,,,,,,
diff --git a/regs/maple_bus_ft0.ods b/regs/maple_bus_ft0.ods
index 55a72af..c9d3363 100644
Binary files a/regs/maple_bus_ft0.ods and b/regs/maple_bus_ft0.ods differ
diff --git a/scene.cpp b/scene.cpp
index 5212a62..4896bad 100644
--- a/scene.cpp
+++ b/scene.cpp
@@ -49,11 +49,11 @@ struct scene_quad_ta_parameters {
 
 static_assert((sizeof (scene_quad_ta_parameters)) == 32 * 4);
 
-uint32_t scene_transform_quad(uint32_t * _scene)
+uint32_t scene_transform_quad(uint32_t * _scene, uint32_t base_color)
 {
   auto scene = reinterpret_cast<scene_quad_ta_parameters *>(&_scene[0]);
 
-  uint32_t base_color = 0xffffff00;
+  //uint32_t base_color = 0xffffff00;
   scene->sprite = global_sprite(base_color);
   scene->vertex = vertex_sprite_type_0(scene_quad[0].x * 240 + 320,
 				       scene_quad[0].y * 240 + 240,
diff --git a/scene.h b/scene.h
index 0bade7f..9a6eade 100644
--- a/scene.h
+++ b/scene.h
@@ -2,6 +2,6 @@
 
 #include <cstdint>
 
-uint32_t scene_transform_quad(uint32_t * scene);
+uint32_t scene_transform_quad(uint32_t * scene, uint32_t color);
 
 uint32_t scene_transform(uint32_t * scene);