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1.1.1.2 root 1: /* Screen Conversion, Spec512 to 320x16Bit */
1.1 root 2:
3: void ConvertSpec512_320x16Bit(void)
4: {
1.1.1.2 root 5: Uint32 *edi, *ebp;
6: Uint16 *esi;
7: register Uint32 eax, ebx, ecx, edx;
8:
9: Spec512_StartFrame(); /* Start frame, track palettes */
10:
11: edx = 0; /* Clear index for loop */
12:
13: ScrY = STScreenStartHorizLine; /* Starting line in ST screen */
14:
15: do /* y-loop */
16: {
17:
18: Spec512_StartScanLine(); /* Build up palettes for every 4 pixels, store in 'ScanLinePalettes' */
19: edx = 0; /* Clear index for loop */
20:
21: /* Get screen addresses, 'edi'-ST screen, 'ebp'-Previous ST screen, 'esi'-PC screen */
22: eax = STScreenLineOffset[ScrY] + STScreenLeftSkipBytes; /* Offset for this line + Amount to skip on left hand side */
23: edi = (Uint32 *)((Uint8 *)pSTScreen + eax); /* ST format screen 4-plane 16 colours */
24: ebp = (Uint32 *)((Uint8 *)pSTScreenCopy + eax); /* Previous ST format screen */
1.1.1.3 root 25: esi = (Uint16 *)pPCScreenDest; /* PC format screen */
1.1 root 26:
1.1.1.2 root 27: ScrX=STScreenWidthBytes>>3; /* Amount to draw across in 16-pixels (8 bytes) */
28:
29: do /* x-loop */
30: {
31: ebx = *edi; /* Do 16 pixels at one time */
32: ecx = *(edi+1);
1.1 root 33:
1.1.1.4 ! root 34: #if SDL_BYTEORDER == SDL_LIL_ENDIAN
! 35:
1.1.1.2 root 36: /* Convert planes to byte indices - as works in wrong order store to workspace so can read back in order! */
37: LOW_BUILD_PIXELS_0 ; /* Generate 'ecx' as pixels [4,5,6,7] */
38: PixelWorkspace[1] = ecx;
39: LOW_BUILD_PIXELS_1 ; /* Generate 'ecx' as pixels [12,13,14,15] */
40: PixelWorkspace[3] = ecx;
41: LOW_BUILD_PIXELS_2 ; /* Generate 'ecx' as pixels [0,1,2,3] */
42: PixelWorkspace[0] = ecx;
43: LOW_BUILD_PIXELS_3 ; /* Generate 'ecx' as pixels [8,9,10,11] */
44: PixelWorkspace[2] = ecx;
45:
1.1.1.3 root 46: /* And plot, the Spec512 is offset by 1 pixel and works on 'chunks' of 4 pixels */
47: /* So, we plot 1_4_4_3 to give 16 pixels, changing palette between */
48: /* (last one is used for first of next 16-pixels) */
49: ecx = PixelWorkspace[0];
50: PLOT_SPEC512_LEFT_LOW_320_16BIT(0) ;
51: Spec512_UpdatePaletteSpan();
52:
1.1.1.4 ! root 53: ecx = *(Uint32 *)( ((Uint8 *)PixelWorkspace)+1 );
1.1.1.3 root 54: PLOT_SPEC512_MID_320_16BIT(1) ;
55: Spec512_UpdatePaletteSpan();
56:
57: ecx = *(Uint32 *)( ((Uint8 *)PixelWorkspace)+5 );
58: PLOT_SPEC512_MID_320_16BIT(5) ;
59: Spec512_UpdatePaletteSpan();
60:
61: ecx = *(Uint32 *)( ((Uint8 *)PixelWorkspace)+9 );
62: PLOT_SPEC512_MID_320_16BIT(9) ;
63: Spec512_UpdatePaletteSpan();
64:
65: ecx = *(Uint32 *)( ((Uint8 *)PixelWorkspace)+13 );
66: PLOT_SPEC512_END_LOW_320_16BIT(13) ;
67:
1.1.1.4 ! root 68: #else
! 69: /* Well, I didn't get the code above working on big-endian machines, too,
! 70: But I hope the following lines are good enough to also do the job... - THH */
! 71:
! 72: LOW_BUILD_PIXELS_0 ;
! 73: PixelWorkspace[3] = ecx;
! 74: LOW_BUILD_PIXELS_1 ;
! 75: PixelWorkspace[1] = ecx;
! 76: LOW_BUILD_PIXELS_2 ;
! 77: PixelWorkspace[2] = ecx;
! 78: LOW_BUILD_PIXELS_3 ;
! 79: PixelWorkspace[0] = ecx;
! 80:
! 81: ecx = PixelWorkspace[0];
! 82: PLOT_SPEC512_MID_320_16BIT(0) ;
! 83: Spec512_UpdatePaletteSpan();
! 84:
! 85: ecx = PixelWorkspace[1];
! 86: PLOT_SPEC512_MID_320_16BIT(4) ;
! 87: Spec512_UpdatePaletteSpan();
! 88:
! 89: ecx = PixelWorkspace[2];
! 90: PLOT_SPEC512_MID_320_16BIT(8) ;
! 91: Spec512_UpdatePaletteSpan();
! 92:
! 93: ecx = PixelWorkspace[3];
! 94: PLOT_SPEC512_MID_320_16BIT(12) ;
! 95: Spec512_UpdatePaletteSpan();
! 96:
! 97: #endif
! 98:
1.1.1.2 root 99: esi += 16; /* Next PC pixels */
100: edi += 2; /* Next ST pixels */
101: ebp += 2; /* Next ST copy pixels */
102: }
103: while( --ScrX ); /* Loop on X */
1.1 root 104:
1.1.1.2 root 105: Spec512_EndScanLine();
1.1 root 106:
1.1.1.2 root 107: pPCScreenDest = (void *)(((unsigned char *)pPCScreenDest)+PCScreenBytesPerLine); /* Offset to next line */
108: ScrY += 1;
109: }
110: while( ScrY < STScreenEndHorizLine ); /* Loop on Y */
111:
112: bScreenContentsChanged = TRUE;
1.1 root 113:
114: }
1.1.1.2 root 115:
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