Android Question Convert C code to B4A

FreeWolF

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Hello, I need to convert that C code to B4A.

B4X:
WORD CRC16 (const BYTE *nData, WORD wLength)
{
static const WORD wCRCTable[] = {
0X0000, 0XC0C1, 0XC181, 0X0140, 0XC301, 0X03C0, 0X0280, 0XC241,
0XC601, 0X06C0, 0X0780, 0XC741, 0X0500, 0XC5C1, 0XC481, 0X0440,
0XCC01, 0X0CC0, 0X0D80, 0XCD41, 0X0F00, 0XCFC1, 0XCE81, 0X0E40,
0X0A00, 0XCAC1, 0XCB81, 0X0B40, 0XC901, 0X09C0, 0X0880, 0XC841,
0XD801, 0X18C0, 0X1980, 0XD941, 0X1B00, 0XDBC1, 0XDA81, 0X1A40,
0X1E00, 0XDEC1, 0XDF81, 0X1F40, 0XDD01, 0X1DC0, 0X1C80, 0XDC41,
0X1400, 0XD4C1, 0XD581, 0X1540, 0XD701, 0X17C0, 0X1680, 0XD641,
0XD201, 0X12C0, 0X1380, 0XD341, 0X1100, 0XD1C1, 0XD081, 0X1040,
0XF001, 0X30C0, 0X3180, 0XF141, 0X3300, 0XF3C1, 0XF281, 0X3240,
0X3600, 0XF6C1, 0XF781, 0X3740, 0XF501, 0X35C0, 0X3480, 0XF441,
0X3C00, 0XFCC1, 0XFD81, 0X3D40, 0XFF01, 0X3FC0, 0X3E80, 0XFE41,
0XFA01, 0X3AC0, 0X3B80, 0XFB41, 0X3900, 0XF9C1, 0XF881, 0X3840,
0X2800, 0XE8C1, 0XE981, 0X2940, 0XEB01, 0X2BC0, 0X2A80, 0XEA41,
0XEE01, 0X2EC0, 0X2F80, 0XEF41, 0X2D00, 0XEDC1, 0XEC81, 0X2C40,
0XE401, 0X24C0, 0X2580, 0XE541, 0X2700, 0XE7C1, 0XE681, 0X2640,
0X2200, 0XE2C1, 0XE381, 0X2340, 0XE101, 0X21C0, 0X2080, 0XE041,
0XA001, 0X60C0, 0X6180, 0XA141, 0X6300, 0XA3C1, 0XA281, 0X6240,
0X6600, 0XA6C1, 0XA781, 0X6740, 0XA501, 0X65C0, 0X6480, 0XA441,
0X6C00, 0XACC1, 0XAD81, 0X6D40, 0XAF01, 0X6FC0, 0X6E80, 0XAE41,
0XAA01, 0X6AC0, 0X6B80, 0XAB41, 0X6900, 0XA9C1, 0XA881, 0X6840,
0X7800, 0XB8C1, 0XB981, 0X7940, 0XBB01, 0X7BC0, 0X7A80, 0XBA41,
0XBE01, 0X7EC0, 0X7F80, 0XBF41, 0X7D00, 0XBDC1, 0XBC81, 0X7C40,
0XB401, 0X74C0, 0X7580, 0XB541, 0X7700, 0XB7C1, 0XB681, 0X7640,
0X7200, 0XB2C1, 0XB381, 0X7340, 0XB101, 0X71C0, 0X7080, 0XB041,
0X5000, 0X90C1, 0X9181, 0X5140, 0X9301, 0X53C0, 0X5280, 0X9241,
0X9601, 0X56C0, 0X5780, 0X9741, 0X5500, 0X95C1, 0X9481, 0X5440,
0X9C01, 0X5CC0, 0X5D80, 0X9D41, 0X5F00, 0X9FC1, 0X9E81, 0X5E40,
0X5A00, 0X9AC1, 0X9B81, 0X5B40, 0X9901, 0X59C0, 0X5880, 0X9841,
0X8801, 0X48C0, 0X4980, 0X8941, 0X4B00, 0X8BC1, 0X8A81, 0X4A40,
0X4E00, 0X8EC1, 0X8F81, 0X4F40, 0X8D01, 0X4DC0, 0X4C80, 0X8C41,
0X4400, 0X84C1, 0X8581, 0X4540, 0X8701, 0X47C0, 0X4680, 0X8641,
0X8201, 0X42C0, 0X4380, 0X8341, 0X4100, 0X81C1, 0X8081, 0X4040 };

BYTE nTemp;
WORD wCRCWord = 0xFFFF;

  while (wLength--)
  {
  nTemp = *nData++ ^ wCRCWord;
  wCRCWord >>= 8;
  wCRCWord ^= wCRCTable[nTemp];
  }
  return wCRCWord;

}

But I need that sub and how can use it....

Finally if I input that string (for example)

11 01 00 03 00 0C

The calculated CRC must be

CE9F

According to that table:

30mxzs4.png



There's a people can do it?

Please, I am desperate... :(

UPDATE: I have found WHAT I NEED. That program is written in VB6, I need to port it into B4A. Is a Modbus CRC16 calculator:

B4X:
http://speedy.sh/4tEkf/CRC16-1.zip
 
Last edited:

FreeWolF

Active Member
Licensed User
Longtime User
This is the code I have estrapolated:

B4X:
Function CRC16(B$) As Long  'Calculates CRC for Each Block

Dim I As Integer
Dim ByteVal As Byte

CRC_H = &HFF  'Reset for Each Text Block
CRC_L = &HFF

For I = 1 To Len(B$)  'Calculate for Length of Block
  ByteVal = Asc(Mid$(B$, I, 1))
   
  CRC16_Update4Bits ((ByteVal And &HF0) / 16) ';  // High nibble first
  CRC16_Update4Bits (ByteVal And &HF)  ';  // Low nibble
Next I
CRC16 = ((CRC_H) * 256) + CRC_L
End Function

Function CRC16_Update4Bits(bVal As Byte)


Dim temp As Byte

  temp = ((Int(CRC_H / 16) And (&HF)) Xor bVal) And (&HF)
   
  ' Shift the CRC Register left 4 bits
   
  CRC_H = (Int(CRC_H * 16) And (&HF0)) Or (Int(CRC_L / 16) And (&HF))
  CRC_L = (CRC_L * 16) And (&HF0)
   
  ' Do the table lookups and XOR the result into the CRC Tables
   
  CRC_H = CRC_H Xor CRC16_LookupHigh(temp)
  CRC_L = CRC_L Xor CRC16_LookupLow(temp)
   
End Function

Function CRC16_LookupHigh(t As Byte)
Dim LookUpHigh
LookUpHigh = Array(&H0, &H10, &H20, &H30, &H40, &H50, &H60, &H70, _
  &H81, &H91, &HA1, &HB1, &HC1, &HD1, &HE1, &HF1)
  CRC16_LookupHigh = LookUpHigh(t)
End Function
Function CRC16_LookupLow(t As Byte)
Dim LookUpLow
LookUpLow = Array(&H0, &H21, &H42, &H63, &H84, &HA5, &HC6, &HE7, _
  &H8, &H29, &H4A, &H6B, &H8C, &HAD, &HCE, &HEF)
  CRC16_LookupLow = LookUpLow(t)
End Function
' unsigned char buff[]={01,0x10,0x20,00,00,05,0x0A,00,01,00,00,00,00,00,01,00,03};
' calcula crc = 0xB13D para meter no bus como 0x3D, 0xB1
' uau! funciona para o ModBus!
Function vCRC16(Message() As Byte) As Integer
  Dim I As Long, J As Long, Odd As Boolean
  vCRC16 = -1
  For I = 0 To UBound(Message)
  vCRC16 = (vCRC16 And &HFF00) Or ((vCRC16 And 255) Xor Message(I))
  For J = 1 To 8
  Odd = vCRC16 And 1
  vCRC16 = ((vCRC16 And &HFFFE) \ 2) And &H7FFF 'shift right
  If Odd Then vCRC16 = &HA001 Xor vCRC16
  Next
  Next
End Function
 
Upvote 0

Erel

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Staff member
Licensed User
Longtime User
Here (written in B4J):
B4X:
Sub Process_Globals
   Private table() As Short = Array As Short(0X0000, 0XC0C1, 0XC181, 0X0140, 0XC301, 0X03C0, 0X0280, 0XC241, _
     0XC601, 0X06C0, 0X0780, 0XC741, 0X0500, 0XC5C1, 0XC481, 0X0440, _
     0XCC01, 0X0CC0, 0X0D80, 0XCD41, 0X0F00, 0XCFC1, 0XCE81, 0X0E40, _
     0X0A00, 0XCAC1, 0XCB81, 0X0B40, 0XC901, 0X09C0, 0X0880, 0XC841, _
     0XD801, 0X18C0, 0X1980, 0XD941, 0X1B00, 0XDBC1, 0XDA81, 0X1A40, _
     0X1E00, 0XDEC1, 0XDF81, 0X1F40, 0XDD01, 0X1DC0, 0X1C80, 0XDC41, _
     0X1400, 0XD4C1, 0XD581, 0X1540, 0XD701, 0X17C0, 0X1680, 0XD641, _
     0XD201, 0X12C0, 0X1380, 0XD341, 0X1100, 0XD1C1, 0XD081, 0X1040, _
     0XF001, 0X30C0, 0X3180, 0XF141, 0X3300, 0XF3C1, 0XF281, 0X3240, _
     0X3600, 0XF6C1, 0XF781, 0X3740, 0XF501, 0X35C0, 0X3480, 0XF441, _
     0X3C00, 0XFCC1, 0XFD81, 0X3D40, 0XFF01, 0X3FC0, 0X3E80, 0XFE41, _
     0XFA01, 0X3AC0, 0X3B80, 0XFB41, 0X3900, 0XF9C1, 0XF881, 0X3840,  _
     0X2800, 0XE8C1, 0XE981, 0X2940, 0XEB01, 0X2BC0, 0X2A80, 0XEA41, _
     0XEE01, 0X2EC0, 0X2F80, 0XEF41, 0X2D00, 0XEDC1, 0XEC81, 0X2C40, _
     0XE401, 0X24C0, 0X2580, 0XE541, 0X2700, 0XE7C1, 0XE681, 0X2640, _
     0X2200, 0XE2C1, 0XE381, 0X2340, 0XE101, 0X21C0, 0X2080, 0XE041, _
     0XA001, 0X60C0, 0X6180, 0XA141, 0X6300, 0XA3C1, 0XA281, 0X6240, _
     0X6600, 0XA6C1, 0XA781, 0X6740, 0XA501, 0X65C0, 0X6480, 0XA441, _
     0X6C00, 0XACC1, 0XAD81, 0X6D40, 0XAF01, 0X6FC0, 0X6E80, 0XAE41, _
     0XAA01, 0X6AC0, 0X6B80, 0XAB41, 0X6900, 0XA9C1, 0XA881, 0X6840, _
     0X7800, 0XB8C1, 0XB981, 0X7940, 0XBB01, 0X7BC0, 0X7A80, 0XBA41, _
     0XBE01, 0X7EC0, 0X7F80, 0XBF41, 0X7D00, 0XBDC1, 0XBC81, 0X7C40, _
     0XB401, 0X74C0, 0X7580, 0XB541, 0X7700, 0XB7C1, 0XB681, 0X7640, _
     0X7200, 0XB2C1, 0XB381, 0X7340, 0XB101, 0X71C0, 0X7080, 0XB041, _
     0X5000, 0X90C1, 0X9181, 0X5140, 0X9301, 0X53C0, 0X5280, 0X9241, _
     0X9601, 0X56C0, 0X5780, 0X9741, 0X5500, 0X95C1, 0X9481, 0X5440, _
     0X9C01, 0X5CC0, 0X5D80, 0X9D41, 0X5F00, 0X9FC1, 0X9E81, 0X5E40, _
     0X5A00, 0X9AC1, 0X9B81, 0X5B40, 0X9901, 0X59C0, 0X5880, 0X9841, _
     0X8801, 0X48C0, 0X4980, 0X8941, 0X4B00, 0X8BC1, 0X8A81, 0X4A40, _
     0X4E00, 0X8EC1, 0X8F81, 0X4F40, 0X8D01, 0X4DC0, 0X4C80, 0X8C41, _
     0X4400, 0X84C1, 0X8581, 0X4540, 0X8701, 0X47C0, 0X4680, 0X8641, _
     0X8201, 0X42C0, 0X4380, 0X8341, 0X4100, 0X81C1, 0X8081, 0X4040 )
End Sub

Sub AppStart (Args() As String)
   Dim res() As Int = CRC16(Array As Byte(0x11, 0x01, 0x00, 0x03, 0x00, 0x0C))
   Log("Hi: " & Bit.ToHexString(res(0)))
   Log("Low: " & Bit.ToHexString(res(1)))
End Sub

Sub CRC16 (Data() As Byte) As Int()
   Dim temp As Int
   Dim CRCword As Int = 0xFFFF
   For i = 0 To Data.Length - 1
     temp = Bit.AND(0xFF, Bit.Xor(Data(i), CRCword))
     CRCword = Bit.AND(0xFFFF, Bit.ShiftRight(CRCword, 8))
     CRCword = Bit.AND(0xFFFF, Bit.Xor (CRCword, table(temp)))
   Next
   Return Array As Int(Bit.AND(0xFF, CRCword), Bit.ShiftRight(Bit.AND(0xFF00, CRCword), 8))
End Sub
 
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FreeWolF

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Sorry for my late reply but Thank you Erel,the fact is that I spent almost the whole weekend to look for a solution to the problem and when I found I turned off the brain because I'd had enough :(
 
Last edited:
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