Sensoray 614 Caption Overlay User Manual
Page 17
With an indirect access method as shown below, to load the caption character
fonts or overlay bitmap-blocks:
#define
G_CAPRAMDATA
0x08
// Caption RAM data[15:0]
#define
G_CAPRAMINDEX
0x0A
// Caption RAM index[15:0]
fpga_reg_write ( b, G_CAPRAMINDEX, capovlRamStart );
for
( i = 0; i <8; i++ )
{
fpga_reg_write ( b, G_CAPRAMDATA, capovlData[i] );
}
In the example above, it’s an one-char/blk-by-one-char/blk base loading sample.
Consider a caption character font (8x16 pixels/char) or an overlay bitmap block
(8x16 pixels/blk), consisted of
Char-byte[0]
bitmap-byte[0]
Char-byte[1]
bitmap-byte[1]
Char-byte[2]
bitmap-byte[2]
Char-byte[3]
bitmap-byte[3]
Char-byte[4]
bitmap-byte[4]
Char-byte[5]
bitmap-byte[5]
Char-byte[6]
bitmap-byte[6]
Char-byte[7]
or
bitmap-byte[7]
Char-byte[8]
bitmap-byte[8]
Char-byte[9]
bitmap-byte[9]
Char-byte[10]
bitmap-byte[10]
Char-byte[11]
bitmap-byte[11]
Char-byte[12]
bitmap-byte[12]
Char-byte[13]
bitmap-byte[13]
Char-byte[14]
bitmap-byte[14]
Char-byte[15]
bitmap-byte[15]
the
capovlData
[8] should be formed like:
capovlData[0] =
Char-byte[1];
// or bitmap-byte[1]
capovlData[0] = capovlData[0]<<8 +
Char-bits[0]
// or bitmap-byte[0]
capovlData[1] =
Char-byte[3];
// or bitmap-byte[3]
capovlData[1] = capovlData[1]<<8 +
Char-bits[2]
// or bitmap-byte[2]
capovlData[2] =
Char-byte[5];
// or bitmap-byte[5]
capovlData[2] = capovlData[2]<<8 +
Char-bits[4]
// or bitmap-byte[4]
capovlData[3] =
Char-byte[7];
// or bitmap-byte[7]
capovlData[3] = capovlData[3]<<8 +
Char-bits[6]
// or bitmap-byte[6]
capovlData[4] =
Char-byte[9];
// or bitmap-byte[9]
capovlData[4] = capovlData[4]<<8 +
Char-bits[8]
// or bitmap-byte[8]
capovlData[5] =
Char-byte[11];
// or bitmap-byte[11]
capovlData[5] = capovlData[5]<<8 +
Char-bits[10] // or bitmap-byte[10]
capovlData[6] =
Char-byte[13];
// or bitmap-byte[13]
capovlData[6] = capovlData[6]<<8 +
Char-bits[12] // or bitmap-byte[12]
capovlData[7] =
Char-byte[15];
// or bitmap-byte[15]
capovlData[7] = capovlData[7]<<8 +
Char-bits[14] // or bitmap-byte[14]
In the char-byte[ ] or bitmap-byte[ ], when bit=1, the pixel will be overlaid; while
when bit=0, the pixel will not be overlaid, but could be transparent or with a
background.