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VDP2 library
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1.Guide
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1.1 Purpose
- Conceals hardware-related processing and reduces the burden on application creators who use VDP2 functions such as displaying images on scroll screens.
- By using this library, register settings can be made without much awareness of V-BLANK.
Hiding the hardware-related processing of V-BLANK interrupt processing reduces the burden on application creators.
V-BLANK interrupt handling routine and frame change setting routine for VDP1 and VDP2 display are provided.
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1.2 Description
- VDP2 only allows access to registers and color RAM during the V-BLANK period. Many registers are not readable.
∙ The VDP2 library has a register buffer in the library, and writing / reading to a normal register is performed on this register buffer and copied to the register during the next V-BLANK period. (Refer to the reference for register buffer details)
This library is roughly divided into the following function groups. I will explain each.
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[Initialization function]
- Must be executed first when using the VDP2 library.
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[Table creation & data set function]
- Set various parameters with reference to the VDP2 user's manual and reference.
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[Operations related to the display screen]
- You can move, enlarge / reduce, and rotate the scroll screen.
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[Line screen setting function]
- Set the line screen and back screen data.
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[Window setting function]
- Set the window.
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[VDP1-related functions]
- This function must be set to display the contents of the frame buffer of VDP1 (Sprite).
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[Color RAM related functions]
- Set pallet or rewrite palette.
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