
from enum import IntEnum

HDR_CHAR = 0x01 # [SOH]
'''The header char (SOH)'''



ACK_CHAR = 0x06 # [ACK]
'''The acknowledgement char (ACK)'''

NAK_CHAR = 0x15 # [NAK]
'''The non acknowledgement char (NAK)'''

CRC_POLYNOMIAL  = 0x1021
'''CRC polynomial value'''

CRC_INITIAL    = 0xFFFF
'''CRC initial value'''

CRC_TAB = (
  0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50A5, 0x60C6, 0x70E7,
  0x8108, 0x9129, 0xA14A, 0xB16B, 0xC18C, 0xD1AD, 0xE1CE, 0xF1EF,
  0x1231, 0x0210, 0x3273, 0x2252, 0x52B5, 0x4294, 0x72F7, 0x62D6,
  0x9339, 0x8318, 0xB37B, 0xA35A, 0xD3BD, 0xC39C, 0xF3FF, 0xE3DE,
  0x2462, 0x3443, 0x0420, 0x1401, 0x64E6, 0x74C7, 0x44A4, 0x5485,
  0xA56A, 0xB54B, 0x8528, 0x9509, 0xE5EE, 0xF5CF, 0xC5AC, 0xD58D,
  0x3653, 0x2672, 0x1611, 0x0630, 0x76D7, 0x66F6, 0x5695, 0x46B4,
  0xB75B, 0xA77A, 0x9719, 0x8738, 0xF7DF, 0xE7FE, 0xD79D, 0xC7BC,
  0x48C4, 0x58E5, 0x6886, 0x78A7, 0x0840, 0x1861, 0x2802, 0x3823,
  0xC9CC, 0xD9ED, 0xE98E, 0xF9AF, 0x8948, 0x9969, 0xA90A, 0xB92B,
  0x5AF5, 0x4AD4, 0x7AB7, 0x6A96, 0x1A71, 0x0A50, 0x3A33, 0x2A12,
  0xDBFD, 0xCBDC, 0xFBBF, 0xEB9E, 0x9B79, 0x8B58, 0xBB3B, 0xAB1A,
  0x6CA6, 0x7C87, 0x4CE4, 0x5CC5, 0x2C22, 0x3C03, 0x0C60, 0x1C41,
  0xEDAE, 0xFD8F, 0xCDEC, 0xDDCD, 0xAD2A, 0xBD0B, 0x8D68, 0x9D49,
  0x7E97, 0x6EB6, 0x5ED5, 0x4EF4, 0x3E13, 0x2E32, 0x1E51, 0x0E70,
  0xFF9F, 0xEFBE, 0xDFDD, 0xCFFC, 0xBF1B, 0xAF3A, 0x9F59, 0x8F78,
  0x9188, 0x81A9, 0xB1CA, 0xA1EB, 0xD10C, 0xC12D, 0xF14E, 0xE16F,
  0x1080, 0x00A1, 0x30C2, 0x20E3, 0x5004, 0x4025, 0x7046, 0x6067,
  0x83B9, 0x9398, 0xA3FB, 0xB3DA, 0xC33D, 0xD31C, 0xE37F, 0xF35E,
  0x02B1, 0x1290, 0x22F3, 0x32D2, 0x4235, 0x5214, 0x6277, 0x7256,
  0xB5EA, 0xA5CB, 0x95A8, 0x8589, 0xF56E, 0xE54F, 0xD52C, 0xC50D,
  0x34E2, 0x24C3, 0x14A0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
  0xA7DB, 0xB7FA, 0x8799, 0x97B8, 0xE75F, 0xF77E, 0xC71D, 0xD73C,
  0x26D3, 0x36F2, 0x0691, 0x16B0, 0x6657, 0x7676, 0x4615, 0x5634,
  0xD94C, 0xC96D, 0xF90E, 0xE92F, 0x99C8, 0x89E9, 0xB98A, 0xA9AB,
  0x5844, 0x4865, 0x7806, 0x6827, 0x18C0, 0x08E1, 0x3882, 0x28A3,
  0xCB7D, 0xDB5C, 0xEB3F, 0xFB1E, 0x8BF9, 0x9BD8, 0xABBB, 0xBB9A,
  0x4A75, 0x5A54, 0x6A37, 0x7A16, 0x0AF1, 0x1AD0, 0x2AB3, 0x3A92,
  0xFD2E, 0xED0F, 0xDD6C, 0xCD4D, 0xBDAA, 0xAD8B, 0x9DE8, 0x8DC9,
  0x7C26, 0x6C07, 0x5C64, 0x4C45, 0x3CA2, 0x2C83, 0x1CE0, 0x0CC1,
  0xEF1F, 0xFF3E, 0xCF5D, 0xDF7C, 0xAF9B, 0xBFBA, 0x8FD9, 0x9FF8,
  0x6E17, 0x7E36, 0x4E55, 0x5E74, 0x2E93, 0x3EB2, 0x0ED1, 0x1EF0)
'''Precomputed CRC values'''

class MsgReaderState(IntEnum):
    '''Message reader state'''
    IDLE =  0
    '''The reader is idle. Nothing was read.'''
    EMPTY = 1
    '''The reader was activated by the arrival of the header character. The message is still empty.'''
    FUNC = 2
    '''The `FUNC` section was read'''
    EXT = 3
    '''The reader is reading the `EXT` section'''
    DEV = 4
    '''The reader is reading the `DEV` section'''
    ADDR = 5
    '''The reader is reading the `ADDR` section'''
    DATA = 6 
    '''The reader is reading the `DATA` section'''
    CHECK = 7
    '''The reader is reading the `CHECK` section'''
    COMPLETE = 8
    '''Message reading is complete'''
    ACKNOWLEDGEMENT = 9
    '''Message is an acknowledgement'''
    ERROR = 10
    '''There was an error reading'''
    
class MsgType(IntEnum):
    '''Message type according DAPI2 protocol'''
    
    ACKNOWLEDGEMENT = -1
    
    READ      = 0x00
    '''Message to read one or more registers.'''
    XREAD     = 0x10
    '''Extended message to read one or more registers. Not yet implemented.'''
    WRITE     = 0x80
    '''Message to write one or more registers.'''
    XWRITE    = 0x90
    '''Extended message to write one or more registers. Not yet implemented.'''
    COMMAND   = 0x20
    '''Command message.'''
    XCOMMAND  = 0x30
    '''Extended command message. Not yet implemented.'''
    RESERVED  = 0xA0
    '''Reserved message. Not yet implemented.'''
    XRESERVED = 0xB0
    '''Extended reserved message. Not yet implemented.'''
    
    
    
ASCII_CONTROL_CHARS = ('NUL','SOH','STX','ETX','EOT','ENQ','ACK','BEL','BS','TAB','LF','VT','FF','CR','SO','SI',
                     'DLE','DC1','DC2','DC3','DC4','NAK','SYN','ETB','CAN','EM','SUB','ESC','FS','GS','RS','US')
'''Naming of ASCII control characters.'''

def buffer2str(buffer):
    '''Convert buffer 2 string for display.
    
    :param bytearray buffer: Buffer to convert
    
    :return: The string
    :rtype: str 
    '''
    
    s = '' 
    if isinstance(buffer, (bytes,bytearray)):    
        for c in buffer:
            if c < 32:
                s+= '['+ASCII_CONTROL_CHARS[c]+']'
            else:
                s+=chr(c)
    else:
        for c in buffer:
            if ord(c)<32:
                s+= '['+ASCII_CONTROL_CHARS[ord(c)]+']'
            else:
                s+=c
    return s

def crcByte(b, crc):
    return CRC_TAB[ (crc >> 8)^ b ] ^ (crc << 8) & 0xffff

def crcChar(c, crc):
    return crcByte(ord(c),crc)

def crcStr(s, crc): 
    for c in s:
        crc = crcChar(c,crc)
    return crc
    
    