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Flags, Counters and Bitmaps

These are implemented by a software-only driver that mimics a set of VPINs that can be used for both digital and analogue values.
Unlike sensors and leds, these VPINs are both INPUT and OUTPUT These can be used in many ways:

  • As a simple digital flag to assist in inter-thread communication.
  • A flag or value that can be set from commands and tested in EXRAIL.(e.g. to stop a sequence)
  • As a counter for looping or occupancy counts such as trains passing over a multi track road crossing.
  • As a collection of 16 digital bits that can be set, reset, toggled, masked and tested.

Existing <> and exrail commands for vpins work on these pins.

Creating virtual pins

  HAL(Bitmap,firstpin,npins)

creates 1 or more virtual pins in software.

e.g. HAL(Bitmap,1000,20) creates pins 1000..1019

Use as flags

When used as a digital flag, these pins can be changed or tested with the basic digital pin commands common to all VPINs. SET, RESET, BLINK, IF, ONBUTTON, ONSENSOR and so forth. Serial commands operate in the same way.

Use as counters

For loop counting, counters can be incremented by BITMAP_INC(1013) and decremented by BITMAP_DEC(1013) and tested with IF/IFNOT/IFGTE etc.

Counters be used to automate a multi track crossing where each train entering increments the counter and decrements it on clearing the crossing. Crossing gate automation can be started when the value changes from 0, and be stopped when the counter returns to 0.

Detecting the first increment from 0 to 1 can be done with ONBUTTON(1013) and the automation can use IF(1013) or IFNOT(1013) to detect when it needs to reopen the road gates.

Use as analogue values (advanced)

Analog values may be set into the virtual pins and tested using the existing analog value commands and exrail macros. <z vpin value> <D ANIN vpin> etc. and in EXRAIL ANOUT(vpin,value,0,0)

Use as binary flag groups (advanced)

Virtual pins (and others that respond to an analog read in order to provide bit mapped digital data, such as SensorCam) can be set and tested with new special EXRAIL commands

IFBITMAP_ALL(vpin,mask) Bitwise ANDs the the vpin value with the mask value and is true if ALL the 1 bits in the mask are also 1 bits in the value. e.g. IFBITMAP_ALL(1013,0x0f) would be true if ALL the last 4 bits of the value are 1s.

IFBITMAP_ANY(1013,0x0f) would be true if ANY of the last 4 bits are 1s.

Modifying bitmap values

BITMAP_AND(vpin,mask) performs a bitwise AND operation. BITMAP_OR(vpin,mask) performs a bitwise OR operation BITMAP_XOR(vpin,mask) performs a bitwise EXCLUSIVE OR (which is basically a toggle).