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/* Copyright (c) 1998, 1999, 2003, 2004 Lance Arsenault, (GNU GPL (v2+))
*/
class Source;
class Field;
class LinearField : public Field
{
public:
// value = count * step + offset
inline LinearField(Source *source,
value_t step_in=(value_t)1.0,
value_t offset_in=(value_t)0.0):
Field(source),
step(step_in), offset(offset_in)
{
_isIncreasing = (step > 0.0)? true: false;
_numberOfValues = MAXCOUNT;
_max = (_numberOfValues-1)*step + offset;
_min = offset;
// assuming that count_t is unsigned so that -1 is the maxmum
// value
index = 0;
setLabel("linear field");
char label[64];
snprintf(label, 64, "step=%g offset=%g", step, offset);
setName(label);
}
// read the list and advance the pointer to the next value in the
// series.
inline value_t read(void)
{
return step*(index++) + offset;
}
// find the minimum values in the range of indexes
// indexing starts at 0.
inline value_t max(count_t i_max=((count_t) -1), count_t i_min=0)
{
if(i_max == ((count_t) -1))
i_max = _numberOfValues - 1;
if(step > (value_t) 0.0)
return step*(i_max) + offset;
else
return step*(i_min) + offset;
}
// find the maximum values in the range of indexes
// indexing starts at 0.
inline value_t min(count_t i_max=((count_t) -1), count_t i_min=0)
{
if(i_max == ((count_t) -1))
i_max = _numberOfValues - 1;
if(step < (value_t) 0.0)
return step*(i_max) + offset;
else
return step*(i_min) + offset;
}
// move the pointer to the first value.
inline void rewind(void) { index = 0; }
struct Dequeuer
{
count_t index, numberOfValuesMinus1;
};
void *makeDequeuer(count_t number_of_values);
void destroyDequeuer(void *dequeuer);
// You can use this to read.
inline value_t read(void *dequeuer)
{
struct Dequeuer *d = (struct Dequeuer *) dequeuer;
value_t val = step*(d->index) + offset;
if(d->index < d->numberOfValuesMinus1)
(d->index)++;
return val;
}
// You can use this to read backwards.
inline value_t readBack(void *dequeuer)
{
struct Dequeuer *d = (struct Dequeuer *) dequeuer;
value_t val = step*(d->index) + offset;
if(d->index > 0)
(d->index)--;
return val;
}
// The FieldReader object can use this to rewind.
inline void rewind(void *dequeuer)
{
((struct Dequeuer *) dequeuer)->index = 0;
}
private:
// Index to the element to be read.
count_t index;
value_t step, offset;
};
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