# BITOPS

> [HTML Version](bitopssbr.htm)

_Reviewed and revised April 2024_

**xcall BITOPS, opcode, chfld, pos, result, result2**

BITOPS was developed to facilitate the use of large bit fields (bitmaps). These are quite useful when you want to keep a single binary flag for each of many items. The bit field can be held in memory in a variable of type X, or in a random file.  

**Parameters**

_opcode  _([Num](num.htm.md))  \[in\]

specifies the operation using the following values:

| **Value** | **Meaning** |
|------|------|
| 1 | Clear bit #_<pos>_; if_ <pos>_ = -1 or is omitted, clear all bits in bitmap |
| 2 | Set bit #_<pos>_; if_ <pos>_ = -1 or is omitted, set all bits in bitmap |
| 3 | Counts all bits in bitmap; return number of 0s in _result_, number of 1s in _result2_ |
| 4 | Set _result_ to bit number of first zero bit on or after given _pos_. If no more zero bits, return –1. At same time, set _result2_ to bit number of first one bit on or after _pos_. |




_chfld_  ([BLOB](blob.htm.md) or [Unsigned Int](integer-unsigned.htm.md))  \[in\]  

is either the bit field (if type X) of any size (first bit is considered bit #0); if any type other than X, _chfld_ is interpreted as an open random file channel (containing the bit field).

_pos  _([Num](num.htm.md))  \[in\]

specifies the bit number we are operating on or starting from; see _opcode_ table above.

_result, result2  _([Num](num.htm.md))  \[out\]

are used to return the results; see _opcode_ table above.