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saved 68 bytes

This commit is contained in:
Christian Kroll 2011-09-25 01:49:52 +00:00
parent c176376b0b
commit 2a81b8e743
1 changed files with 17 additions and 24 deletions
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41
animations/bitmapscroller.c
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@ -25,17 +25,17 @@ typedef struct bitmap_t
unsigned char nXDomain; /**< Last valid x-coordinate for viewport. */
unsigned char nYDomain; /**< Last valid y-coordinate for viewport. */
unsigned char nChunkDomain; /**< Last valid chunk for viewport. */
unsigned char nChunkCount; /**< Amount of horiz. chunks of the bitmap. */
unsigned char nChunkCount; /**< Amount of horiz. chunks of the bitmap.*/
}
bitmap_t;
/**
* This function generates an eight-by-one pixel chunk for a given pair of pixel
* coordinates and a borg plane number. The resulting chunk can be copied
* directly to the borg's frame buffer. It makes use of the user provided
* "getChunk" function which in contrast only accepts chunk based coordinates
* (resulting in chunks whose x-coordinates are always a multiple of eight) and
* coordinates and a borg plane index. The resulting chunk can be copied
* directly to the borg's frame buffer. It utilizes the user provided "getChunk"
* function which in contrast only accepts chunk based coordinates (resulting in
* chunks whose pixel based x-coordinates are always a multiple of eight) and
* uses bit planes which defer from the plane scheme used by the borg's frame
* buffer.
* @param pBitmap The bitmap of interest.
@ -55,25 +55,20 @@ static unsigned char bitmap_getAlignedChunk(bitmap_t const *const pBitmap,
unsigned char nChunk = 0xFF;
unsigned char nMask = 1;
unsigned char const nAlignment = x % 8;
unsigned char const x_8 = x / 8;
// we have to go through every bit plane
for (unsigned char i = 0; i < pBitmap->nBitPlanes; ++i)
for (unsigned char i = pBitmap->nBitPlanes; i--;)
{
// generate chunk
unsigned char nPlaneChunk;
// if the given x-coordinate is aligned to a chunk coordinate we can
// reuse the result of the "getChunk" function directly.
if (nAlignment == 0)
{
nPlaneChunk = pBitmap->fpGetChunk(i, x/8, y, pBitmap->nFrame);
}
nPlaneChunk = pBitmap->fpGetChunk(i, x_8, y, pBitmap->nFrame)
<< nAlignment;
// in case of misalignment we combine two chunks with chunk based
// coordinates into one chunk which aligns to the given x-coordinate
else
if (nAlignment != 0)
{
nPlaneChunk = pBitmap->fpGetChunk(i, x/8, y, pBitmap->nFrame)
<< nAlignment;
nPlaneChunk |= pBitmap->fpGetChunk(i, x/8+1, y, pBitmap->nFrame)
nPlaneChunk |= pBitmap->fpGetChunk(i, x_8 + 1, y, pBitmap->nFrame)
>> (8 - nAlignment);
}
@ -106,6 +101,9 @@ static void bitmap_drawViewport(bitmap_t const *const pBitmap,
{
for (unsigned char x = 0; x < pBitmap->nViewportWidth; x += 8)
{
// determine correct column within frame buffer
unsigned char const nCol = pBitmap->nChunkCount - 1 - (x / 8);
for (unsigned char p = NUMPLANE; p--;)
{
// retrieve a chunk which can be copied into the frame buffer
@ -128,16 +126,14 @@ static void bitmap_drawViewport(bitmap_t const *const pBitmap,
nX, nY + y) >> (8 - NUM_COLS % 8);
}
#endif
// determine correct column within frame buffer
uint8_t const nCol = pBitmap->nChunkCount - 1 - (x / 8);
// copy chunk into corresponding frame buffer plane
pixmap[p][y][nCol] = nChunk;
// if a bit in plane p + 1 is set, the corresponding bit in p
// has to be set as well
if (p < (NUMPLANE - 1))
{
pixmap[p][y][nCol] |= pixmap[p + 1][y][nCol];
nChunk |= pixmap[p + 1][y][nCol];
}
// copy chunk into corresponding frame buffer plane
pixmap[p][y][nCol] = nChunk;
}
}
}
@ -215,9 +211,6 @@ void bitmap_scroll(unsigned char const nWidth,
signed char dx = 0;
signed char dy = 0;
// remove garbage from screen
clear_screen(0);
for (bitmap.nFrame = 0; bitmap.nFrame < nFrameCount; ++bitmap.nFrame)
{
bitmap_drawViewport(&bitmap, x, y);