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I could stop if I wanted to! (eliminated 28 bytes)

This commit is contained in:
Christian Kroll 2012-08-24 19:04:25 +00:00
parent ca61149aa2
commit 0f7dc22fb8
1 changed files with 23 additions and 21 deletions
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44
animations/fpmath_patterns.c
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@ -340,10 +340,12 @@ static void fixDrawPattern(fixp_t const t_start,
fpmath_pattern_func_t fpPattern,
void *r)
{
// off-screen buffer
unsigned char pOffScreen[NUMPLANE + 1][NUM_ROWS][LINEBYTES];
for (fixp_t t = t_start; t < t_stop; t += t_delta)
{
// For performance reasons we draw the pattern to an off-screen buffer
// 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.
@ -355,27 +357,27 @@ static void fixDrawPattern(fixp_t const t_start,
}
}
// better safe than sorry
#if ((NUM_ROWS * LINEBYTES) < 256)
typedef unsigned char bitmap_offset_t;
#else
typedef unsigned int bitmap_offset_t;
#endif
// last byte of the frame buffer
unsigned char *pPixmap =
&pixmap[NUMPLANE - 1][NUM_ROWS - 1][LINEBYTES - 1];
// last byte of 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
unsigned char *pOffscreenDistLow =
&pOffScreen[NUMPLANE - 1][NUM_ROWS - 1][LINEBYTES - 1];
// Here we transcribe the off-screen contents to the actual frame buffer
// by distributing down 8 bits in parallel (per iteration).
for (bitmap_offset_t nOffset = sizeof(pixmap[0]); nOffset--;)
// by distributing down 8 bits in parallel per iteration. We start at
// the end of both buffers and move backwards through their space.
while (pPixmap >= (unsigned char *)pixmap) // stop at the beginning
{
// for whatever reason, gcc produces leaner code if "p" is of type
// "unsigned int" as opposed to "unsigned char"
for (unsigned int p = NUMPLANE; p--;)
{
(&pixmap[p][0][0])[nOffset] =
(&pOffScreen[p + 1][0][0])[nOffset];
(&pOffScreen[p][0][0])[nOffset] |=
(&pOffScreen[p + 1][0][0])[nOffset];
(&pOffScreen[p + 1][0][0])[nOffset] = 0;
}
// actually draw off-screen contents
*(pPixmap--) = *pOffscreenDistHigh;
// distribute bits down to the next lower plane
*(pOffscreenDistLow--) |= *pOffscreenDistHigh;
// clear already drawn off-screen contents
*(pOffscreenDistHigh--) = 0;
}
// wait a moment to ensure that the current frame is visible
@ -413,7 +415,7 @@ typedef struct fixp_plasma_s
/**
* Draws a plasma like pattern (sort of... four shades of grey are pretty
* Generates a plasma like pattern (sort of... four shades of grey are pretty
* scarce for a neat plasma animation). This is realized by superimposing two
* functions which generate independent patterns for themselves.
*
@ -496,7 +498,7 @@ typedef struct fixp_psychedelic_s
/**
* Draws flowing circular waves with a rotating center.
* Generates flowing circular waves with a rotating center.
* @param x x-coordinate
* @param y y-coordinate
* @param t A step value which changes for each frame, allowing for animations.