On 06/01/2015 21:22, Kevin O'Connor wrote:
> On Tue, Jan 06, 2015 at 08:59:09PM +0100, Paolo Bonzini wrote:
>> On 06/01/2015 16:49, Kevin O'Connor wrote:
>>> + if (vga_emulate_text()) {
>>> + // Read bottom right pixel of the cell to guess bg color
>>> + op.y += cheight-1;
>>> + handle_gfx_op(&op);
>>> + op.y -= cheight-1;
>>> + bgattr = op.pixels[7];
>>> + fgattr = bgattr ^ 0x7;
>>> + car = 1;
>>> + }
>>
>> It's better to use the top right pixel. The bottom right has a false
>> positive for characters 23 and 95.
>
> Hrmm. How did you test? The script I wrote shows the bottom right as
> the least number of false positives. With the 8x16 font, there are
> six false positives, but all six are mirror images of other characters
> so there is no way to avoid them.
I used the 8x8 font. I suspect that my new favorite testcase (gwbasic,
what else) will mess up PRINT "_" if you use the bottom right.
Paolo
> -Kevin
>
>
> $ python ./scripts/countbits.py < vgasrc/vgafonts.c
> 256
> 49 83 107 129 113 82 51 16
> 58 101 110 98 100 103 61 19
> 78 146 139 132 146 132 72 29
> 92 136 122 140 154 122 63 17
> 108 159 142 139 154 147 88 44
> 81 135 124 116 134 132 59 14
> 66 123 132 152 134 101 66 13
> 22 31 42 57 44 30 28 11
>
> 256
> 6 8 21 41 23 21 19 8
> 14 24 40 57 41 32 26 7
> 44 78 102 125 110 102 65 13
> 48 93 92 92 93 110 76 12
> 51 90 92 99 95 99 81 15
> 80 146 129 132 138 141 89 26
> 85 133 109 134 133 140 95 18
> 99 151 121 134 138 149 114 39
> 86 129 88 111 120 130 92 13
> 80 116 84 105 113 134 90 10
> 47 109 126 148 122 136 83 10
> 12 16 25 39 30 31 26 6
> 9 16 28 47 30 27 22 9
> 6 7 20 33 20 20 20 6
>
> 256
> 6 8 21 41 23 21 19 8
> 15 24 40 57 41 33 27 7
> 41 72 95 118 100 89 59 20
> 43 88 90 85 82 93 75 20
> 51 83 79 92 81 91 81 21
> 81 140 126 134 138 134 94 31
> 79 130 98 122 131 131 89 25
> 110 153 119 140 146 142 120 52
> 82 130 91 107 111 120 92 24
> 85 127 87 103 112 125 95 17
> 87 117 71 100 105 130 96 18
> 49 115 134 154 122 136 90 15
> 9 13 23 40 28 31 23 8
> 8 13 25 38 29 30 25 8
> 8 11 23 41 25 22 19 8
> 6 7 20 33 20 20 20 6
>
> ==================================== countbits.py script
>
> import sys
>
> count = 0
> counts = []
> for line in sys.stdin:
> if 'vgafont' in line:
> if counts:
> print count
> for i in range(len(counts)):
> print "%3d" % counts[i],
> if i % 8 == 7:
> print
> print
> count = 0
> counts = []
> try:
> parts = [int(p.strip(), 0) for p in line.split(',') if p.strip()]
> except ValueError:
> continue
> if not parts:
> continue
> count += 1
> out = [0] * (len(parts) * 8)
> for i in range(len(parts)):
> p = parts[i]
> for j in range(8):
> if (1<<(7-j)) & p:
> out[i*8 + j] += 1
> if not counts:
> counts = out
> else:
> for i in range(len(out)):
> counts[i] += out[i]
>
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