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crates/specialized/rtx-neuro-io/src/ctf/constants.rs

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+//! CTF MEG Format Constants
+//!
+//! Constants for parsing CTF MEG data files.
+
+/// MEG4 file magic header for version 4.1
+pub const MEG4_MAGIC_V41: &[u8; 8] = b"MEG41CP\0";
+
+/// MEG4 file magic header for version 4.2
+pub const MEG4_MAGIC_V42: &[u8; 8] = b"MEG42CP\0";
+
+/// RES4 file magic header for version 4.1
+pub const RES4_MAGIC_V41: &[u8; 8] = b"MEG41RS\0";
+
+/// RES4 file magic header for version 4.2
+pub const RES4_MAGIC_V42: &[u8; 8] = b"MEG42RS\0";
+
+/// Maximum number of coils per sensor
+pub const MAX_COILS: usize = 8;
+
+/// Maximum channel name length
+pub const MAX_CHANNEL_NAME: usize = 32;
+
+/// Size of the MEG4 header in bytes
+pub const MEG4_HEADER_SIZE: usize = 8;
+
+/// Size of each sample in bytes (int32)
+pub const SAMPLE_SIZE: usize = 4;
+
+/// Maximum MEG4 file size (2GB limit)
+pub const MAX_MEG4_FILE_SIZE: u64 = 2_147_483_648;
+
+// ============================================================================
+// Channel type constants
+// ============================================================================
+
+/// MEG magnetometer/gradiometer channel
+pub const CTF_MEG_CH: i16 = 0;
+
+/// Reference MEG channel
+pub const CTF_REF_MEG_CH: i16 = 1;
+
+/// EEG channel
+pub const CTF_EEG_CH: i16 = 2;
+
+/// Stimulus/trigger channel
+pub const CTF_STIM_CH: i16 = 3;
+
+/// Analog to digital channel
+pub const CTF_ADC_CH: i16 = 4;
+
+/// Head localization coil channel
+pub const CTF_HLC_CH: i16 = 5;
+
+/// Digital input channel
+pub const CTF_DIN_CH: i16 = 6;
+
+/// Digital auxiliary channel
+pub const CTF_DAC_CH: i16 = 7;
+
+/// SCLK channel (system clock)
+pub const CTF_SCLK_CH: i16 = 8;
+
+/// SAM (synthetic aperture magnetometry) channel
+pub const CTF_SAM_CH: i16 = 9;
+
+/// Virtual channel
+pub const CTF_VIRTUAL_CH: i16 = 10;
+
+/// System channel
+pub const CTF_SYS_CH: i16 = 11;
+
+// ============================================================================
+// Sensor type constants
+// ============================================================================
+
+/// Reference magnetometer
+pub const CTF_REF_MAG: i16 = 0;
+
+/// Reference gradiometer
+pub const CTF_REF_GRAD: i16 = 1;
+
+/// CTF 275 system MEG sensor
+pub const CTF_275_MAG: i16 = 2;
+
+/// CTF 275 system reference
+pub const CTF_275_REF: i16 = 3;
+
+// ============================================================================
+// Gradient order constants
+// ============================================================================
+
+/// No gradient compensation
+pub const CTF_NO_GRAD: i16 = 0;
+
+/// First order gradient compensation
+pub const CTF_G1BR: i16 = 1;
+
+/// Second order gradient compensation
+pub const CTF_G2BR: i16 = 2;
+
+/// Third order gradient compensation
+pub const CTF_G3BR: i16 = 3;
+
+// ============================================================================
+// RES4 file structure sizes (based on CTF specification)
+// ============================================================================
+
+/// Size of general header section
+pub const RES4_GENERAL_HEADER_SIZE: usize = 1844;
+
+/// Size of each channel info entry
+pub const RES4_CHANNEL_INFO_SIZE: usize = 1360;
+
+/// Offset to number of channels in header
+pub const RES4_NCHAN_OFFSET: usize = 1288;
+
+/// Offset to sampling frequency in header
+pub const RES4_SFREQ_OFFSET: usize = 1296;
+
+/// Offset to number of samples in header
+pub const RES4_NSAMP_OFFSET: usize = 1304;
+
+/// Offset to number of trials in header
+pub const RES4_NTRIALS_OFFSET: usize = 1312;
+
+/// Offset to channel info section
+pub const RES4_CHANNEL_INFO_OFFSET: usize = 1844;
+
+// ============================================================================
+// Channel info offsets within RES4_CHANNEL_INFO_SIZE block
+// ============================================================================
+
+/// Offset to channel name (32 bytes string)
+pub const CH_NAME_OFFSET: usize = 0;
+
+/// Offset to channel type (i16)
+pub const CH_TYPE_OFFSET: usize = 32;
+
+/// Offset to sensor type (i16)
+pub const CH_SENSOR_TYPE_OFFSET: usize = 34;
+
+/// Offset to proper gain (f64)
+pub const CH_PROPER_GAIN_OFFSET: usize = 48;
+
+/// Offset to q_gain (f64)
+pub const CH_Q_GAIN_OFFSET: usize = 56;
+
+/// Offset to io_gain (f64)
+pub const CH_IO_GAIN_OFFSET: usize = 64;
+
+/// Offset to io_offset (f64)
+pub const CH_IO_OFFSET_OFFSET: usize = 72;
+
+/// Offset to number of coils (i16)
+pub const CH_NUM_COILS_OFFSET: usize = 80;
+
+/// Offset to gradient order (i16)
+pub const CH_GRAD_ORDER_OFFSET: usize = 82;
+
+/// Offset to first coil position (starts coil array)
+pub const CH_COILS_OFFSET: usize = 96;
+
+/// Size of each coil info entry
+pub const COIL_INFO_SIZE: usize = 112;
+
+// ============================================================================
+// Coil info offsets within COIL_INFO_SIZE block
+// ============================================================================
+
+/// Offset to coil position X (f64)
+pub const COIL_POS_X_OFFSET: usize = 0;
+
+/// Offset to coil position Y (f64)
+pub const COIL_POS_Y_OFFSET: usize = 8;
+
+/// Offset to coil position Z (f64)
+pub const COIL_POS_Z_OFFSET: usize = 16;
+
+/// Offset to coil orientation X (f64)
+pub const COIL_ORI_X_OFFSET: usize = 24;
+
+/// Offset to coil orientation Y (f64)
+pub const COIL_ORI_Y_OFFSET: usize = 32;
+
+/// Offset to coil orientation Z (f64)
+pub const COIL_ORI_Z_OFFSET: usize = 40;
+
+/// Offset to coil area (f64)
+pub const COIL_AREA_OFFSET: usize = 48;
+
+/// Offset to coil turns (i32)
+pub const COIL_TURNS_OFFSET: usize = 56;