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## Re: [ft] what's the mean of CEIL( x )?

**From**: |
David Turner |

**Subject**: |
Re: [ft] what's the mean of CEIL( x )? |

**Date**: |
Fri, 19 May 2006 09:29:48 +0200 |

**User-agent**: |
Thunderbird 1.5 (Windows/20051201) |

luoyi a écrit :

sorry, maybe I misunderstand what is "fixed-point 26.6 number".....
can you explain it ?

`
`

`it means that the value of X can be seen as a 26-bit integer, followed
``by a 6-bit
`fractional part. As in the following graphics:
+----------------------------------+-----------+
| integer mantissa | fraction |
+----------------------------------+-----------+
26 bits 6 bits

`
``
`In other words:
float_value(x) = (x >> 6) + (x & 63)/64.0
round(x) = (x+32) & ~63
floor(x) = x & ~63
ceil(x) = (x+63) & ~63
int(x) = (x >> 6)
the macro CEIL(x) as defined really returns int(ceil(x))
note that int(x) is (x >> 6) and *not* x/64.0 !!
Hope this helps,
- David Turner
- The FreeType Project (www.freetype.org)

`
``
`

"David Turner" <address@hidden> ??????:address@hidden

`
` x=240 corresponds to value 3.75 CEIL(240) => 4

`
`

240 / 26.6 = 9.022
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`
`

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