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add BurnNibbleExpand();

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This commit is contained in:
dinkc64 2019-07-02 19:39:55 -04:00
parent de7b479d31
commit 1707c41355
2 changed files with 35 additions and 1 deletions
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33
src/burn/burn.cpp
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@ -850,6 +850,39 @@ INT32 BurnByteswap(UINT8* pMem, INT32 nLen)
return 0;
}
// useful for expanding 4bpp pixels packed into one byte using little to-no
// extra memory.
// use 'swap' to swap whether the high or low nibble goes into byte 0 or 1
// 'nxor' is useful for inverting the data
// this is an example of a graphics decode that can be converted to use this
// function:
// INT32 Plane[4] = { STEP4(0,1) }; - 0,1,2,3
// INT32 XOffs[8] = { STEP8(0,4) }; - 0,4,8,12,16,20,24,28 (swap is useful for when this is 4,0,12,8...)
// INT32 YOffs[8] = { STEP8(0,32) }; - 0, 32, 64, 96, 128, 160, 192, 224
//
void BurnNibbleExpand(UINT8 *source, UINT8 *dst, INT32 length, INT32 swap, UINT8 nxor)
{
if (source == NULL) {
bprintf (0, _T("BurnNibbleExpand() source passed as NULL!\n"));
return;
}
if (length <= 0) {
bprintf (0, _T("BurnNibbleExpand() length passed as <= 0 (%d)!\n"), length);
return;
}
swap = swap ? 1 : 0;
if (dst == NULL) dst = source;
for (INT32 i = length - 1; i >= 0; i--)
{
INT32 t = source[i] ^ nxor;
dst[(i * 2 + 0) ^ swap] = t >> 4;
dst[(i * 2 + 1) ^ swap] = t & 0xf;
}
}
// Application-defined rom loading function:
INT32 (__cdecl *BurnExtLoadRom)(UINT8 *Dest, INT32 *pnWrote, INT32 i) = NULL;

3
src/burn/burnint.h
View File

@ -77,7 +77,8 @@ struct BurnDriver {
// burn.cpp
INT32 BurnSetRefreshRate(double dRefreshRate);
INT32 BurnByteswap(UINT8* pm,INT32 nLen);
INT32 BurnByteswap(UINT8* pMem, INT32 nLen);
void BurnNibbleExpand(UINT8 *source, UINT8 *dst, INT32 length, INT32 swap, UINT8 nxor);
INT32 BurnClearScreen();
// load.cpp