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Index > OS Construction > VESA 32 bit color modes

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SeproMan



Joined: 11 Oct 2009
Posts: 60
Location: Belgium
SeproMan
VESA documentation states about the DirectColorModeInfo field : "Bit D1 specifies wether the bits in the Rsvd field of the direct color pixel can be used by the application or are reserved, and thus unusable."

If this bit is ON the bits in the Rsvd field are usable by the application and so I can use a single doubleword instruction with whatever value I like in its fourth byte.

If this bit is OFF the bits in the Rsvd field are reserved.
May I modify only the first 24 bits (requiring multiple instructions)?
Must I use a single doubleword instruction with a fourth byte equal to zero?
Can I still use a single doubleword instruction with any value in the fourth byte?

_________________
Real Address Mode.
Post 12 Aug 2012, 13:32
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freecrac



Joined: 19 Oct 2011
Posts: 117
Location: Germany Hamburg
freecrac
SeproMan wrote:
VESA documentation states about the DirectColorModeInfo field : "Bit D1 specifies wether the bits in the Rsvd field of the direct color pixel can be used by the application or are reserved, and thus unusable."

If this bit is ON the bits in the Rsvd field are usable by the application and so I can use a single doubleword instruction with whatever value I like in its fourth byte.

If this bit is OFF the bits in the Rsvd field are reserved.
May I modify only the first 24 bits (requiring multiple instructions)?
Must I use a single doubleword instruction with a fourth byte equal to zero?
Can I still use a single doubleword instruction with any value in the fourth byte?

VBE3pdf
Quote:

Bit D1 specifies whether the bits in the Rsvd field of the direct color pixel can be used by the application or are reserved, and thus unusable.
D1 = Bits in Rsvd field are usable/reserved
0 = Bits in Rsvd field are reserved
1 = Bits in Rsvd field are usable by the application

I never become problems with 32 bits per pixels with to set a single doubleword instruction with any value in the fourth byte, if we become a field position of RGBX and a mask size of 8:8:8:8 using the direct color model.
(DirectColorModeInfo (Modeinfobuffer+27h) = 0)

Dirk
Post 13 Aug 2012, 07:33
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