---
name: "fixmul"
section: "3alleg4"
platform: "linux"
package: "allegro4-doc"
version: "2:4.4.3.1-5"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/fixmul/3alleg4"
---

# fixmul(3alleg4)

Multiplies two fixed point values together. Allegro game programming library.

## NAME

fixmul - Multiplies two fixed point values together. Allegro game programming library.

## SYNOPSIS

**#include \<allegro.h\>**

**fixed fixmul(fixed x, fixed y);**

## DESCRIPTION

A fixed point value can be multiplied or divided by an integer with the  normal \`\*' and \`/' operators. To multiply two fixed point values, though, you must use this function.

If an overflow occurs, \`errno' will be set and the maximum possible value will be returned, but \`errno' is not cleared if the operation is successful. This means that if you are going to test for overflow you should set \`errno=0' before calling fixmul(). Example:

```
   fixed result;
   /* This will put 30000 into `result'. */
   result = fixmul(itofix(10), itofix(3000));
   /* But this overflows, and sets `errno'. */
   result = fixmul(itofix(100), itofix(3000));
   ASSERT(!errno);
```

## RETURN VALUE

Returns the clamped result of multiplying \`x' by \`y', setting \`errno' to ERANGE if there was an overflow.

## SEE ALSO

**fixadd**(3alleg4), **fixsub**(3alleg4), **fixdiv**(3alleg4), **ex3buf**(3alleg4), **excustom**(3alleg4), **exfixed**(3alleg4), **exspline**(3alleg4), **exstars**(3alleg4), **exupdate**(3alleg4)