113 lines
2.9 KiB
C
113 lines
2.9 KiB
C
/*
|
|
|
|
ucg_ccs.c
|
|
|
|
color component slide sub library
|
|
|
|
Universal uC Color Graphics Library
|
|
|
|
Copyright (c) 2013, olikraus@gmail.com
|
|
All rights reserved.
|
|
|
|
Redistribution and use in source and binary forms, with or without modification,
|
|
are permitted provided that the following conditions are met:
|
|
|
|
* Redistributions of source code must retain the above copyright notice, this list
|
|
of conditions and the following disclaimer.
|
|
|
|
* Redistributions in binary form must reproduce the above copyright notice, this
|
|
list of conditions and the following disclaimer in the documentation and/or other
|
|
materials provided with the distribution.
|
|
|
|
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
|
|
CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
|
|
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
|
|
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
|
|
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
|
|
CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
|
|
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
|
|
NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
|
|
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
|
|
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
|
|
STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
|
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
|
|
ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
|
|
e: end
|
|
n: steps
|
|
|
|
|
|
f(0) = s
|
|
f(n) = e
|
|
f(x) = m*x + s
|
|
f(n-1) = m*(n-1) + s =!= e
|
|
--> m = (e-s)/n
|
|
f(x) = (e-s)/(n-1) * x + s
|
|
f(0) = s
|
|
f(1) = s + (e-s)/(n-1)
|
|
|
|
*/
|
|
|
|
#include "ucg.h"
|
|
|
|
/*
|
|
Setup change from "start" to "end" with a specified amount of "steps".
|
|
After calling this procedure, ccs->current will contain the "start" value.
|
|
*/
|
|
void ucg_ccs_init(ucg_ccs_t *ccs, uint8_t start, uint8_t end, ucg_int_t steps)
|
|
{
|
|
ccs->start = start;
|
|
ccs->num = end-start;
|
|
ccs->den = steps-1;
|
|
ccs->dir = 1;
|
|
|
|
ccs->quot = ccs->num / ccs->den;
|
|
if ( ccs->num < 0 )
|
|
{
|
|
ccs->num = -ccs->num;
|
|
ccs->dir = -1;
|
|
}
|
|
ccs->rem = ccs->num % ccs->den;
|
|
|
|
ccs->frac = ccs->den/2;
|
|
ccs->current = start;
|
|
}
|
|
|
|
/*
|
|
Make one step towards the "end" value.
|
|
ccs->curront will contain the updated value.
|
|
*/
|
|
void ucg_ccs_step(ucg_ccs_t *ccs)
|
|
{
|
|
|
|
ccs->current += ccs->quot;
|
|
ccs->frac += ccs->rem;
|
|
if ( ccs->frac >= ccs->den )
|
|
{
|
|
ccs->current += ccs->dir;
|
|
ccs->frac -= ccs->den;
|
|
}
|
|
}
|
|
|
|
/*
|
|
f(x) = (e-s)/(n-1) * x + s
|
|
current = (num / den) * (pos / den)
|
|
|
|
Seek to the specified "pos"ition.
|
|
"pos" must be between 0 and "end"-1
|
|
*/
|
|
void ucg_ccs_seek(ucg_ccs_t *ccs, ucg_int_t pos)
|
|
{
|
|
ucg_int_t p;
|
|
ccs->current = ccs->quot;
|
|
ccs->current *= pos;
|
|
p = ccs->rem * pos + ccs->den/2;
|
|
if ( ccs->dir >= 0 )
|
|
ccs->current += p / ccs->den;
|
|
else
|
|
ccs->current -= p / ccs->den;
|
|
ccs->frac = p % ccs->den;
|
|
ccs->current += ccs->start;
|
|
}
|
|
|