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Started trying to be a bit more explicit about usage, and to divide up drawing responsibility.

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This commit is contained in:
Thomas Harte 2017-02-05 17:51:56 -05:00
parent 23f3ccd77a
commit 6bcf95042c
2 changed files with 42 additions and 11 deletions
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30
Machines/Atari2600/TIA.cpp
View File

@ -126,7 +126,7 @@ void TIA::reset_horizontal_counter()
int TIA::get_cycles_until_horizontal_blank(unsigned int from_offset)
{
return cycles_per_line - (horizontal_counter_ + (int)from_offset) % cycles_per_line;
return 4 + (cycles_per_line - (horizontal_counter_ + (int)from_offset) % cycles_per_line);
}
void TIA::set_background_colour(uint8_t colour)
@ -156,6 +156,8 @@ void TIA::set_playfield(uint16_t offset, uint8_t value)
void TIA::set_playfield_control_and_ball_size(uint8_t value)
{
background_half_mask_ = value & 1;
playfield_is_above_players_ = !!(value & 4);
playfield_is_in_score_mode_ = !playfield_is_above_players_ && (value & 2);
}
void TIA::set_playfield_ball_colour(uint8_t colour)
@ -338,12 +340,8 @@ void TIA::output_for_cycles(int number_of_cycles)
}
if(pixel_target_)
{
while(output_cursor < horizontal_counter_)
{
int offset = (output_cursor - 68) >> 2;
pixel_target_[output_cursor - pixel_target_origin_] = ((background_[(offset/20)&background_half_mask_] >> (offset%20))&1) ? playfield_ball_colour_ : background_colour_;
output_cursor++;
}
draw_background(pixel_target_, output_cursor, horizontal_counter_);
output_cursor = horizontal_counter_;
} else output_cursor = horizontal_counter_;
if(horizontal_counter_ == cycles_per_line)
{
@ -377,3 +375,21 @@ void TIA::output_line()
break;
}
}
#pragma mark - Background and playfield
void TIA::draw_background(uint8_t *target, int start, int length) const
{
if(!target) return;
int position = start;
while(length--)
{
int offset = (position - 68) >> 2;
target[position - pixel_target_origin_] = ((background_[(offset/20)&background_half_mask_] >> (offset%20))&1) ? playfield_ball_colour_ : background_colour_;
position++;
}
}
void TIA::draw_playfield(uint8_t *target, int start, int length) const
{
}

23
Machines/Atari2600/TIA.hpp
View File

@ -23,6 +23,10 @@ class TIA {
NTSC, PAL
};
/*!
Advances the TIA by @c number_of_cycles cycles. Any queued setters take effect in the
first cycle performed.
*/
void run_for_cycles(int number_of_cycles);
void set_output_mode(OutputMode output_mode);
@ -71,9 +75,8 @@ class TIA {
inline void output_for_cycles(int number_of_cycles);
inline void output_line();
inline void draw_background(uint8_t *target, int start, int length);
inline void draw_playfield(uint8_t *target, int start, int length);
inline void draw_background_and_playfield(uint8_t *target, int start, int length);
inline void draw_background(uint8_t *target, int start, int length) const;
inline void draw_playfield(uint8_t *target, int start, int length) const;
// the master counter; counts from 0 to 228 with all visible pixels being in the final 160
int horizontal_counter_;
@ -81,14 +84,25 @@ class TIA {
// contains flags to indicate whether sync or blank are currently active
int output_mode_;
// keeps track of the target pixel buffer for this line and when it was acquired
// keeps track of the target pixel buffer for this line and when it was acquired, and a corresponding collision buffer
uint8_t *pixel_target_;
int pixel_target_origin_;
uint8_t collision_buffer_[160];
enum class CollisionType : uint8_t {
Playfield,
Sprite1,
Sprite2,
Missile1,
Missile2,
Ball
};
// playfield state
uint8_t playfield_ball_colour_;
uint8_t background_colour_;
int background_half_mask_;
bool playfield_is_in_score_mode_;
bool playfield_is_above_players_;
uint32_t background_[2]; // contains two 20-bit bitfields representing the background state;
// at index 0 is the left-hand side of the playfield with bit 0 being
// the first bit to display, bit 1 the second, etc. Index 1 contains
@ -96,6 +110,7 @@ class TIA {
// mirroring mode, background_[0] will be output on the left and
// background_[1] on the right; otherwise background_[0] will be
// output twice.
int latched_playfield_value_;
// player state
struct Player {