cPtr8, cPtr16, cPtr24, cPtr32

Source: Positron8 Compiler User Manual, PDF page 384

Syntax

Variable = cPtr8 (Address) Variable = cPtr16 (Address) Variable = cPtr24 (Address) Variable = cPtr32 (Address)

Overview

Indirectly read flash memory using a variable to hold the 16-bit or 32-bit address. For enhanced 14-bit core devices and 18F devices only.

Parameters

Variable is a user defined variable that holds the result of the indirectly addressed flash memory area. Address is a Word, Long, or Dword variable, or an expression that holds the 16-bit, 24-bit, or 32-bit address of the flash memory area of interest.

Address can also post or pre increment or decrement:

(MyAddress++) Post increment MyAddress after retrieving it’s RAM location. (MyAddress --) Post decrement MyAddress after retrieving it’s RAM location. (++MyAddress) Pre increment MyAddress before retrieving it’s RAM location. (--MyAddress) Pre decrement MyAddress before retrieving it’s RAM location.

cPtr8 will retrieve a value with an optional 8-bit post or pre increment or decrement. cPtr16 will retrieve a value with an optional 16-bit post or pre increment or decrement. cPtr24 will retrieve a value with an optional 24-bit post or pre increment or decrement. cPtr32 will retrieve a value with an optional 32-bit post or pre increment or decrement.

8-bit Example.

'
' Read 8-bit values indirectly from flash memory
'
  Device = 18F26K40
                                       ' Tell the compiler what device to compile for
  Declare Xtal = 16
                                ' Tell the compiler the device is operating at 16MHz
  Declare Hserial_Baud = 9600
'
' Create an 8-bit flash memory table
'
  Dim FlashArray As Flash8 = 1, 2, 3, 4, 5, 6, 7, 8, 9, 0
  Dim MyByte As Byte
                                     ' Create a byte variable
  Dim bIndex As Byte
  Dim wAddress As Word
                                     ' Create variable to hold 16-bit address
Main:
'
' Read from flash memory
'
  wAddress = AddressOf(FlashArray) ' Load wAddress with address of flash memory
  Do
                                     ' Create a loop
     MyByte = cPtr8(wAddress++)    ' Retrieve from code with post increment
     If MyByte = 0 Then Break       ' Exit when a null(0) is read from code
     HRsoutLn Dec MyByte
                                     ' Transmit the byte read from code
  Loop

16-bit Example.

'
' Read 16-bit values indirectly from flash memory
'
  Device = 18F26K40
                                       ' Tell the compiler what device to compile for
  Declare Xtal = 16
                                ' Tell the compiler the device is operating at 16MHz
  Declare Hserial_Baud = 9600
'
' Create a 16-bit flash memory table
'
  Dim FlashArray As Flash16 = 100, 200, 300, 400, 500, 600, 700, 0
  Dim MyWord As Word
                                       ' Create a word variable
  Dim bIndex As Byte
   Dim wAddress As Word
                                       ' Create variable to hold 16-bit address
Main:
'
' Read from flash memory
'
  wAddress = AddressOf(FlashArray)
                                       ' Load wAddress with address of memory
  Do
                                       ' Create a loop
     MyWord = cPtr16(wAddress++)
                                       ' Retrieve from code with post increment
     If MyWord = 0 Then Break
                                       ' Exit when a null(0) is read from code
     HRsoutLn Dec MyWord
                                       ' Transmit the word read from code
  Loop

24-bit Example.

'
' Read 24-bit values indirectly from flash memory
'
  Device = 18F26K40
                                       ' Tell the compiler what device to compile for
  Declare Xtal = 16
                                ' Tell the compiler the device is operating at 16MHz
  Declare Hserial_Baud = 9600
'
' Create a 24-bit flash memory table
'
  Dim FlashArray As Flash24 = 100, 200, 300, 400, 500, 600, 700, 0
  Dim MyLong As Long
                                       ' Create a long variable
  Dim bIndex As Byte
   Dim wAddress As Word
                                       ' Create variable to hold 16-bit address
Main:
'
' Read from flash memory
'
  wAddress = AddressOf(FlashArray)
                                       ' Load wAddress with address of memory
  Do
                                       ' Create a loop
     MyLong = cPtr24(wAddress++)
                                       ' Retrieve from code with post increment
     If MyLong = 0 Then Break
                                       ' Exit when a null(0) is read from code
     HRsoutLn Dec MyLong
                                       ' Transmit the long read from code
  Loop

32-bit Example.

'
' Read 32-bit values indirectly from flash memory
'
  Device = 18F26K40
                                       ' Tell the compiler what device to compile for
  Declare Xtal = 16
                                ' Tell the compiler the device is operating at 16MHz
  Declare Hserial_Baud = 9600
'
' Create a 32-bit flash memory table
'
  Dim FlashArray As Flash32 = 100, 200, 300, 400, 500, 600, 700, 0
  Dim MyDword As Dword
                                       ' Create a dword variable
  Dim bIndex As Byte
  Dim wAddress As Word
                                       ' Create variable to hold 16-bit address
Main:
'
' Read from flash memory
'
  wAddress = AddressOf(FlashArray)
                                       ' Load wAddress with address of memory
  Do
                                       ' Create a loop
     MyDword = cPtr32(wAddress++)
                                       ' Retrieve from code with post increment
     If MyDword = 0 Then Break
                                       ' Exit when a null(0) is read from code
     HRsoutLn Dec MyDword
                                       ' Transmit the dword read from code
  Loop