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Improve documentation.

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This commit is contained in:
Thomas Harte 2022-07-19 16:19:19 -04:00
parent cb42ee3ade
commit feee6afe0f
1 changed files with 11 additions and 1 deletions
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12
Machines/Amiga/Sprites.cpp
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@ -33,21 +33,31 @@ static_assert(expand_sprite_word(0x0000) == 0x00'00'00'00'00'00'00'00);
// MARK: - Sprites.
void Sprite::set_start_position(uint16_t value) {
// b8–b15: low 8 bits of VSTART;
// b0–b7: high 8 bits of HSTART.
v_start_ = (v_start_ & 0xff00) | (value >> 8);
h_start = uint16_t((h_start & 0x0001) | ((value & 0xff) << 1));
}
void Sprite::set_stop_and_control(uint16_t value) {
// b8–b15: low 8 bits of VSTOP;
// b7: attachment flag;
// b3–b6: unused;
// b2: VSTART high bit;
// b1: VSTOP high bit;
// b0: HSTART low bit.
h_start = uint16_t((h_start & 0x01fe) | (value & 0x01));
v_stop_ = uint16_t((value >> 8) | ((value & 0x02) << 7));
v_start_ = uint16_t((v_start_ & 0x00ff) | ((value & 0x04) << 6));
attached = value & 0x80;
// Disarm the sprite, but expect graphics next from DMA.
// Disarm the sprite.
visible = false;
}
void Sprite::set_image_data(int slot, uint16_t value) {
// Store data; also mark sprite as visible (i.e. 'arm' it)
// if data is being stored to slot 0.
data[slot] = value;
visible |= slot == 0;
}