Line-A
The Line-A emulator
The negative Line-A variables
A structure is used for passing parameters to the Line-A functions. This statically created Line-A parameter block is made up as shown below. The number in the comment section gives the offset of the component to the start of the structure in each case.
typedef struct
{
int16_t v_planes, /* 0: # Bit planes (1, 2 or 4) */
v_lin_wr, /* 2: # bytes/scanline */
*contrl,
*intin,
*ptsin, /* 12: Coordinates input */
*intout,
*ptsout, /* 20: Coordinates output */
fg_bp_1, /* 24: Plane 0 */
fg_bp_2, /* 26: Plane 1 */
fg_bp_3, /* 28: Plane 2 */
fg_bp_4, /* 30: Plane 3 */
lstlin; /* 32: Draw last pixel of a line */
/* (1) or don't draw it (0) */
uint16_t ln_mask; /* 34: Line pattern */
int16_t wrt_mode, /* 36: Writing modes */
x1, y1, x2, y2; /* 38: Coordinate */
void *patptr; /* 46: Fill pattern */
uint16_t patmsk; /* 50: Fill pattern "mask" */
int16_t multifill, /* 52: Fill pattern for planes */
clip, /* 54: Flag for clipping */
xmn_clip, ymn_clip,
xmx_clip, ymx_clip, /* 60: Clipping rectangle */
/* Rest for text_blt: */
xacc_dda, /* 64: Set to 0x8000 before text */
/* output */
dda_inc, /* 66: Scaling increment */
t_sclsts, /* 68: Scaling direction */
mono_status, /* 70: Proportional font */
sourcex, sourcey, /* 72: Coordinates in font */
destx, desty, /* 76: Screen coordinates */
delx, dely; /* 80: Width and height of character*/
FONT_HDR *fbase; /* 84: Pointer to font data */
int16_t fwidth, /* 88: Width of font form */
style; /* 90: Font style effect */
uint16_t litemask, /* 92: Mask for light */
skewmask; /* 94: Mask for italic */
int16_t weight, /* 96: Width for bold */
r_off, /* 98: Italic offset right */
l_off, /* 100: Italic offset left */
scale, /* 102: Scaling flag yes/no */
chup, /* 104: Character rotation angle *10 */
text_fg; /* 106: Text foreground colour */
void *scrtchp; /* 108: Pointer to 2 contiguous */
/* scratch buffers */
int16_t scrpt2, /* 112: Index in buffer */
text_bg, /* 114: Unused */
copy_tran, /* 116: -- */
(*fill_abort)( void ); /* 118: Tests seedfill */
} LINEA;
Line-A
The Line-A emulator
The negative Line-A variables