First implementation only sending.

.gitignore

@@ -14,3 +14,8 @@ Cargo.lock
 # MSVC Windows builds of rustc generate these, which store debugging information
 *.pdb
 
+
+
+# Added by cargo
+
+/target

Cargo.toml

@@ -0,0 +1,14 @@
+[package]
+name = "dynamixel"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[lints.clippy]
+pedantic = "warn"
+nursery = "warn"
+unwrap_used = "deny"
+expect_used = "deny"
+
+[dependencies]

src/error.rs

@@ -0,0 +1,42 @@
+#[derive(Debug, PartialEq, Eq, Clone, Copy)]
+pub enum Error {
+    /// Failed to process the sent instruction packet
+    Result,
+    /// Undefined instruction has been used
+    Instruction,
+    /// CRC of the sent packet does not match
+    Crc,
+    /// Data to be written in the corresponding address is outside the range of the minimum /
+    /// maximum value
+    DataRange,
+    /// Attempt to write data that is shorter than the data length of the corresponding address
+    DataLength,
+    /// Data to be written in the corresponding address is outside of the limit value
+    DataLimit,
+    /// Access error (write to read only, read from write only, write to rom in rom lock)
+    Access,
+    /// There is some hardware issue with the device. Check hardware error status for details.
+    Hardware,
+    /// An unknown error code was returned
+    Unknown,
+    /// The buffer is to small
+    BufferSize,
+}
+
+impl Error {
+    /// Converts the error byte from a status packet into a rust result.
+    const fn from_byte(byte: u8) -> Result<(), Self> {
+        match byte & 0x7F {
+            0 if byte & 0x80 == 0 => Ok(()),
+            0 => Err(Self::Hardware),
+            1 => Err(Self::Result),
+            2 => Err(Self::Instruction),
+            3 => Err(Self::Crc),
+            4 => Err(Self::DataRange),
+            5 => Err(Self::DataLength),
+            6 => Err(Self::DataLimit),
+            7 => Err(Self::Access),
+            _ => Err(Self::Unknown), // This shouldn't be possible
+        }
+    }
+}

src/instruction.rs

@@ -0,0 +1,206 @@
+use crate::error::Error;
+
+/// An instruction packet sent from the host to the servo.
+///
+/// Structure:
+/// ```text
+/// 0xFF 0xFF 0xFD 0x00 ID Len_L Len_H Instruction Param1 … ParamN CRC_L CRC_H
+/// ```
+#[derive(Debug)]
+pub struct Packet<'a> {
+    /// which servo to talk to
+    pub id: u8,
+    /// what to send to the servo
+    pub instruction: Instruction<'a>,
+}
+
+#[derive(Debug)]
+pub enum Instruction<'a> {
+    Ping,
+    Read { addr: u16, len: u16 },
+    Write { addr: u16, data: &'a [u8] },
+    RegWrite { addr: u16, data: &'a [u8] },
+    Action,
+    FactoryReset(ResetType),
+    Reboot,
+    Clear,
+    ControlTableBackup(BackupDirection),
+    SyncRead { addr: u16, len: u16, ids: &'a [u8] },
+    SyncWrite { addr: u16, len: u16, data: &'a [u8] },
+    FastSyncRead { addr: u16, len: u16, ids: &'a [u8] },
+    BulkRead { data: &'a [u8] },
+    BulkWrite { data: &'a [u8] },
+    FastBulkRead { data: &'a [u8] },
+}
+
+#[derive(Debug, Clone, Copy)]
+pub enum ResetType {
+    All,
+    AllExceptId,
+    AllExceptIdBaud,
+}
+
+#[derive(Debug, Clone, Copy)]
+pub enum BackupDirection {
+    Store,
+    Restore,
+}
+
+impl<'a> Packet<'a> {
+    /// writes the instruction into the provided buffer.
+    ///
+    /// # Errors
+    ///
+    /// This function will return an error if the provided buffer isn't big enough
+    pub fn to_bytes<'b>(&self, buffer: &'b mut [u8]) -> Result<&'b mut [u8], Error> {
+        if buffer.len() < 10 {
+            return Err(Error::BufferSize);
+        }
+        buffer[..8].copy_from_slice(&[
+            0xFF,
+            0xFF,
+            0xFD,
+            0x00,
+            self.id,
+            0x00,
+            0x00,
+            self.instruction.number(),
+        ]);
+        let len = self.instruction.insert_parameters(&mut buffer[8..])?;
+        buffer[5..7].copy_from_slice(&(len + 3).to_le_bytes());
+        let total_length = len as usize + 10;
+        // let crc = Self::CRC.checksum(&buffer[..total_length - 2]);
+        let crc = Self::crc(&buffer[..total_length - 2]);
+        buffer[total_length - 2..total_length].copy_from_slice(&crc.to_le_bytes());
+        Ok(&mut buffer[..total_length])
+    }
+
+    fn crc(buffer: &[u8]) -> u16 {
+        const CRC_TABLE: [u16; 256] = [
+            0x0000, 0x8005, 0x800F, 0x000A, 0x801B, 0x001E, 0x0014, 0x8011, 0x8033, 0x0036, 0x003C,
+            0x8039, 0x0028, 0x802D, 0x8027, 0x0022, 0x8063, 0x0066, 0x006C, 0x8069, 0x0078, 0x807D,
+            0x8077, 0x0072, 0x0050, 0x8055, 0x805F, 0x005A, 0x804B, 0x004E, 0x0044, 0x8041, 0x80C3,
+            0x00C6, 0x00CC, 0x80C9, 0x00D8, 0x80DD, 0x80D7, 0x00D2, 0x00F0, 0x80F5, 0x80FF, 0x00FA,
+            0x80EB, 0x00EE, 0x00E4, 0x80E1, 0x00A0, 0x80A5, 0x80AF, 0x00AA, 0x80BB, 0x00BE, 0x00B4,
+            0x80B1, 0x8093, 0x0096, 0x009C, 0x8099, 0x0088, 0x808D, 0x8087, 0x0082, 0x8183, 0x0186,
+            0x018C, 0x8189, 0x0198, 0x819D, 0x8197, 0x0192, 0x01B0, 0x81B5, 0x81BF, 0x01BA, 0x81AB,
+            0x01AE, 0x01A4, 0x81A1, 0x01E0, 0x81E5, 0x81EF, 0x01EA, 0x81FB, 0x01FE, 0x01F4, 0x81F1,
+            0x81D3, 0x01D6, 0x01DC, 0x81D9, 0x01C8, 0x81CD, 0x81C7, 0x01C2, 0x0140, 0x8145, 0x814F,
+            0x014A, 0x815B, 0x015E, 0x0154, 0x8151, 0x8173, 0x0176, 0x017C, 0x8179, 0x0168, 0x816D,
+            0x8167, 0x0162, 0x8123, 0x0126, 0x012C, 0x8129, 0x0138, 0x813D, 0x8137, 0x0132, 0x0110,
+            0x8115, 0x811F, 0x011A, 0x810B, 0x010E, 0x0104, 0x8101, 0x8303, 0x0306, 0x030C, 0x8309,
+            0x0318, 0x831D, 0x8317, 0x0312, 0x0330, 0x8335, 0x833F, 0x033A, 0x832B, 0x032E, 0x0324,
+            0x8321, 0x0360, 0x8365, 0x836F, 0x036A, 0x837B, 0x037E, 0x0374, 0x8371, 0x8353, 0x0356,
+            0x035C, 0x8359, 0x0348, 0x834D, 0x8347, 0x0342, 0x03C0, 0x83C5, 0x83CF, 0x03CA, 0x83DB,
+            0x03DE, 0x03D4, 0x83D1, 0x83F3, 0x03F6, 0x03FC, 0x83F9, 0x03E8, 0x83ED, 0x83E7, 0x03E2,
+            0x83A3, 0x03A6, 0x03AC, 0x83A9, 0x03B8, 0x83BD, 0x83B7, 0x03B2, 0x0390, 0x8395, 0x839F,
+            0x039A, 0x838B, 0x038E, 0x0384, 0x8381, 0x0280, 0x8285, 0x828F, 0x028A, 0x829B, 0x029E,
+            0x0294, 0x8291, 0x82B3, 0x02B6, 0x02BC, 0x82B9, 0x02A8, 0x82AD, 0x82A7, 0x02A2, 0x82E3,
+            0x02E6, 0x02EC, 0x82E9, 0x02F8, 0x82FD, 0x82F7, 0x02F2, 0x02D0, 0x82D5, 0x82DF, 0x02DA,
+            0x82CB, 0x02CE, 0x02C4, 0x82C1, 0x8243, 0x0246, 0x024C, 0x8249, 0x0258, 0x825D, 0x8257,
+            0x0252, 0x0270, 0x8275, 0x827F, 0x027A, 0x826B, 0x026E, 0x0264, 0x8261, 0x0220, 0x8225,
+            0x822F, 0x022A, 0x823B, 0x023E, 0x0234, 0x8231, 0x8213, 0x0216, 0x021C, 0x8219, 0x0208,
+            0x820D, 0x8207, 0x0202,
+        ];
+
+        let mut crc_acc = 0u16;
+
+        for byte in buffer {
+            let i = (crc_acc >> 8) as u8 ^ byte;
+            crc_acc = (crc_acc << 8) ^ CRC_TABLE[i as usize];
+        }
+
+        crc_acc
+    }
+}
+
+impl<'a> Instruction<'a> {
+    const fn number(&self) -> u8 {
+        match self {
+            Self::Ping => 0x01,
+            Self::Read { addr: _, len: _ } => 0x02,
+            Self::Write { addr: _, data: _ } => 0x03,
+            Self::RegWrite { addr: _, data: _ } => 0x04,
+            Self::Action => 0x05,
+            Self::FactoryReset(_) => 0x06,
+            Self::Reboot => 0x08,
+            Self::Clear => 0x10,
+            Self::ControlTableBackup(_) => 0x20,
+            Self::SyncRead {
+                addr: _,
+                len: _,
+                ids: _,
+            } => 0x82,
+            Self::SyncWrite {
+                addr: _,
+                len: _,
+                data: _,
+            } => 0x83,
+            Self::FastSyncRead {
+                addr: _,
+                len: _,
+                ids: _,
+            } => 0x8A,
+            Self::BulkRead { data: _ } => 0x92,
+            Self::BulkWrite { data: _ } => 0x93,
+            Self::FastBulkRead { data: _ } => 0x9A,
+        }
+    }
+
+    fn insert_parameters(&self, buffer: &mut [u8]) -> Result<u16, Error> {
+        use Instruction::{
+            Action, BulkRead, BulkWrite, Clear, ControlTableBackup, FactoryReset, FastBulkRead,
+            FastSyncRead, Ping, Read, Reboot, RegWrite, SyncRead, SyncWrite, Write,
+        };
+        match self {
+            Ping | Action | Reboot => Ok(0),
+            Read { addr, len } if buffer.len() >= 4 => {
+                buffer[..2].copy_from_slice(&addr.to_le_bytes());
+                buffer[2..4].copy_from_slice(&len.to_le_bytes());
+                Ok(4)
+            }
+            Write { addr, data } | RegWrite { addr, data } if buffer.len() >= 2 + data.len() => {
+                buffer[..2].copy_from_slice(&addr.to_le_bytes());
+                buffer[2..data.len() + 2].copy_from_slice(data);
+                Ok(2 + u16::try_from(data.len()).map_err(|_| Error::Unknown)?)
+            }
+            FactoryReset(reset) if !buffer.is_empty() => {
+                buffer[0] = match reset {
+                    ResetType::All => 0xFF,
+                    ResetType::AllExceptId => 0x01,
+                    ResetType::AllExceptIdBaud => 0x02,
+                };
+                Ok(1)
+            }
+            Clear if buffer.len() >= 5 => {
+                buffer[..6].copy_from_slice(&[0x01, 0x44, 0x58, 0x4C, 0x22]);
+                Ok(5)
+            }
+            ControlTableBackup(direction) if buffer.len() >= 5 => {
+                buffer[0] = match direction {
+                    BackupDirection::Store => 0x01,
+                    BackupDirection::Restore => 0x02,
+                };
+                buffer[1..6].copy_from_slice(&[0x43, 0x54, 0x52, 0x4C]);
+                Ok(5)
+            }
+            SyncRead { addr, len, ids } | FastSyncRead { addr, len, ids }
+                if buffer.len() >= 4 + ids.len() =>
+            {
+                buffer[..2].copy_from_slice(&addr.to_le_bytes());
+                buffer[2..4].copy_from_slice(&len.to_le_bytes());
+                buffer[4..4 + ids.len()].copy_from_slice(ids);
+                Ok(4 + u16::try_from(ids.len()).map_err(|_| Error::Unknown)?)
+            }
+            SyncWrite {
+                addr: _,
+                len: _,
+                data: _,
+            } => unimplemented!(),
+            BulkRead { data: _ } => unimplemented!(),
+            BulkWrite { data: _ } => unimplemented!(),
+            FastBulkRead { data: _ } => unimplemented!(),
+            _ => Err(Error::BufferSize),
+        }
+    }
+}

src/lib.rs

@@ -0,0 +1,4 @@
+#![no_std]
+
+pub mod error;
+pub mod instruction;