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some speed improvements

This commit is contained in:
Christian Kroll 2012-09-04 01:45:29 +00:00
parent bc59653e9b
commit bcb5e146ce
1 changed files with 32 additions and 19 deletions
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51
animations/fpmath_patterns.c
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@ -11,6 +11,7 @@
#include <assert.h>
#include <stdint.h>
#include <stddef.h>
#include "../config.h"
#include "../pixel.h"
#include "../util.h"
@ -346,38 +347,50 @@ static void fixDrawPattern(fixp_t const t_start,
for (fixp_t t = t_start; t < t_stop; t += t_delta)
{
// For performance reasons the pattern is drawn to an off-screen buffer
// without distributing bits of higher planes down to lower ones. This
// is done afterwards when the off-screen contents are copied to the
// actual frame buffer.
for (unsigned char y = 0; y < NUM_ROWS; ++y)
// without distributing bits of higher planes down to lower ones.
ptrdiff_t nRowColOffset = 0;
for (unsigned char y = 0; y < UNUM_ROWS; ++y)
{
for (unsigned char x = 0; x < (LINEBYTES * 8u); ++x)
{
pOffScreen[fpPattern(x, y, t, r)][y][x / 8] |= shl_table[x % 8];
// Since multidimensional subscript expressions are rather
// expensive, we just resolve the first dimension (which
// represents the plane) and add an offset that correlates to
// the currently processed row and column.
*(&pOffScreen[fpPattern(x, y, t, r)][0][0] + nRowColOffset) |=
shl_table[x % 8u];
// increment the offset after completion of a byte
if ((x % 8u) == 7u)
{
nRowColOffset++;
}
}
}
// last byte of the frame buffer
// one byte behind the frame buffer
unsigned char *pPixmap =
&pixmap[NUMPLANE - 1][NUM_ROWS - 1][LINEBYTES - 1];
// last byte of the off-screen buffer
(&pixmap[NUMPLANE - 1][NUM_ROWS - 1][LINEBYTES - 1]) + 1;
// one byte behind the off-screen buffer
unsigned char *pOffscreenDistHigh =
&pOffScreen[NUMPLANE][NUM_ROWS - 1][LINEBYTES - 1];
// last byte of the second last plane of the off-screen buffer
(&pOffScreen[NUMPLANE][NUM_ROWS - 1][LINEBYTES - 1]) + 1;
// one byte behind the second last plane of the off-screen buffer
unsigned char *pOffscreenDistLow =
&pOffScreen[NUMPLANE - 1][NUM_ROWS - 1][LINEBYTES - 1];
(&pOffScreen[NUMPLANE - 1][NUM_ROWS - 1][LINEBYTES - 1]) + 1;
// Here we transcribe the off-screen contents to the actual frame buffer
// by distributing down 8 bits in parallel per iteration. We start at
// the end of both buffers and move backwards through their space.
// The pre-decrement operator is used so that GCC utilizes the AVR's
// built-in pre-decrement variants of the "ld" and "st" instructions.
while (pPixmap >= (unsigned char *)pixmap) // stop at the beginning
{
// actually draw off-screen contents
*(pPixmap--) = *pOffscreenDistHigh;
*(--pPixmap) = *(--pOffscreenDistHigh);
// distribute bits down to the next lower plane
*(pOffscreenDistLow--) |= *pOffscreenDistHigh;
*(--pOffscreenDistLow) |= *pOffscreenDistHigh;
// clear already drawn off-screen contents
*(pOffscreenDistHigh--) = 0;
*pOffscreenDistHigh = 0;
}
// wait a moment to ensure that the current frame is visible
@ -447,10 +460,10 @@ static unsigned char fixAnimPlasma(unsigned char const x,
{
p->fFunc2CosArg = NUM_ROWS * fixCos(t) + fixScaleUp(NUM_ROWS);
p->fFunc2SinArg = NUM_COLS * fixSin(t) + fixScaleUp(NUM_COLS);
}
if (y == 0)
{
p->fFunc1[x] = fixSin(fixMul(fixScaleUp(x), fPlasmaX) + t);
for (unsigned char i = NUM_COLS; i--;)
{
p->fFunc1[i] = fixSin(fixMul(fixScaleUp(i), fPlasmaX) + t);
}
}
fixp_t const fFunc2 = fixSin(fixMul(fixDist(fixScaleUp(x), fixScaleUp(y),
@ -458,7 +471,7 @@ static unsigned char fixAnimPlasma(unsigned char const x,
uint8_t const nRes = fixScaleDown(fixDiv(fixMul(p->fFunc1[x] + fFunc2 +
fixScaleUp(2), fixScaleUp(NUMPLANE - 1)), fixScaleUp(2)));
assert (nRes <= 3);
assert (nRes <= NUMPLANE);
return nRes;
}