mirror of
https://github.com/TomHarte/CLK.git
synced 2024-11-30 04:50:08 +00:00
401 lines
15 KiB
C++
401 lines
15 KiB
C++
//
|
||
// Blitter.cpp
|
||
// Clock Signal
|
||
//
|
||
// Created by Thomas Harte on 22/07/2021.
|
||
// Copyright © 2021 Thomas Harte. All rights reserved.
|
||
//
|
||
|
||
#include "Blitter.hpp"
|
||
|
||
#include "Minterms.hpp"
|
||
|
||
#include <cassert>
|
||
|
||
#ifndef NDEBUG
|
||
#define NDEBUG
|
||
#endif
|
||
|
||
#define LOG_PREFIX "[Blitter] "
|
||
#include "../../Outputs/Log.hpp"
|
||
|
||
using namespace Amiga;
|
||
|
||
namespace {
|
||
|
||
/// @returns Either the final carry flag or the output nibble when using fill mode given that it either @c is_exclusive fill mode, or isn't;
|
||
/// and the specified initial @c carry and input @c nibble.
|
||
template <bool wants_carry> constexpr uint32_t fill_nibble(bool is_exclusive, uint8_t carry, uint8_t nibble) {
|
||
uint8_t fill_output = 0;
|
||
uint8_t bit = 0x01;
|
||
while(bit < 0x10) {
|
||
auto pre_toggle = nibble & bit, post_toggle = pre_toggle;
|
||
if(!is_exclusive) {
|
||
pre_toggle &= ~carry; // Accept bits that would transition to set immediately.
|
||
post_toggle &= carry; // Accept bits that would transition to clear after the fact.
|
||
} else {
|
||
post_toggle = 0; // Just do the pre-toggle.
|
||
}
|
||
|
||
carry ^= pre_toggle;
|
||
fill_output |= carry;
|
||
carry ^= post_toggle;
|
||
|
||
bit <<= 1;
|
||
carry <<= 1;
|
||
}
|
||
|
||
if constexpr (wants_carry) {
|
||
return carry >> 4;
|
||
} else {
|
||
return fill_output;
|
||
}
|
||
}
|
||
|
||
// Lookup key for these tables is:
|
||
//
|
||
// b0–b3: input nibble
|
||
// b4: carry
|
||
// b5: is_exclusive
|
||
//
|
||
// i.e. it's in the range [0, 63].
|
||
//
|
||
// Tables below are indexed such that the higher-order bits select a table entry, lower-order bits select
|
||
// a bit or nibble from within the indexed item.
|
||
|
||
constexpr uint32_t fill_carries[] = {
|
||
(fill_nibble<true>(false, 0, 0x0) << 0x0) | (fill_nibble<true>(false, 0, 0x1) << 0x1) | (fill_nibble<true>(false, 0, 0x2) << 0x2) | (fill_nibble<true>(false, 0, 0x3) << 0x3) |
|
||
(fill_nibble<true>(false, 0, 0x4) << 0x4) | (fill_nibble<true>(false, 0, 0x5) << 0x5) | (fill_nibble<true>(false, 0, 0x6) << 0x6) | (fill_nibble<true>(false, 0, 0x7) << 0x7) |
|
||
(fill_nibble<true>(false, 0, 0x8) << 0x8) | (fill_nibble<true>(false, 0, 0x9) << 0x9) | (fill_nibble<true>(false, 0, 0xa) << 0xa) | (fill_nibble<true>(false, 0, 0xb) << 0xb) |
|
||
(fill_nibble<true>(false, 0, 0xc) << 0xc) | (fill_nibble<true>(false, 0, 0xd) << 0xd) | (fill_nibble<true>(false, 0, 0xe) << 0xe) | (fill_nibble<true>(false, 0, 0xf) << 0xf) |
|
||
|
||
(fill_nibble<true>(false, 1, 0x0) << 0x10) | (fill_nibble<true>(false, 1, 0x1) << 0x11) | (fill_nibble<true>(false, 1, 0x2) << 0x12) | (fill_nibble<true>(false, 1, 0x3) << 0x13) |
|
||
(fill_nibble<true>(false, 1, 0x4) << 0x14) | (fill_nibble<true>(false, 1, 0x5) << 0x15) | (fill_nibble<true>(false, 1, 0x6) << 0x16) | (fill_nibble<true>(false, 1, 0x7) << 0x17) |
|
||
(fill_nibble<true>(false, 1, 0x8) << 0x18) | (fill_nibble<true>(false, 1, 0x9) << 0x19) | (fill_nibble<true>(false, 1, 0xa) << 0x1a) | (fill_nibble<true>(false, 1, 0xb) << 0x1b) |
|
||
(fill_nibble<true>(false, 1, 0xc) << 0x1c) | (fill_nibble<true>(false, 1, 0xd) << 0x1d) | (fill_nibble<true>(false, 1, 0xe) << 0x1e) | (fill_nibble<true>(false, 1, 0xf) << 0x1f),
|
||
|
||
(fill_nibble<true>(true, 0, 0x0) << 0x0) | (fill_nibble<true>(true, 0, 0x1) << 0x1) | (fill_nibble<true>(true, 0, 0x2) << 0x2) | (fill_nibble<true>(true, 0, 0x3) << 0x3) |
|
||
(fill_nibble<true>(true, 0, 0x4) << 0x4) | (fill_nibble<true>(true, 0, 0x5) << 0x5) | (fill_nibble<true>(true, 0, 0x6) << 0x6) | (fill_nibble<true>(true, 0, 0x7) << 0x7) |
|
||
(fill_nibble<true>(true, 0, 0x8) << 0x8) | (fill_nibble<true>(true, 0, 0x9) << 0x9) | (fill_nibble<true>(true, 0, 0xa) << 0xa) | (fill_nibble<true>(true, 0, 0xb) << 0xb) |
|
||
(fill_nibble<true>(true, 0, 0xc) << 0xc) | (fill_nibble<true>(true, 0, 0xd) << 0xd) | (fill_nibble<true>(true, 0, 0xe) << 0xe) | (fill_nibble<true>(true, 0, 0xf) << 0xf) |
|
||
|
||
(fill_nibble<true>(true, 1, 0x0) << 0x10) | (fill_nibble<true>(true, 1, 0x1) << 0x11) | (fill_nibble<true>(true, 1, 0x2) << 0x12) | (fill_nibble<true>(true, 1, 0x3) << 0x13) |
|
||
(fill_nibble<true>(true, 1, 0x4) << 0x14) | (fill_nibble<true>(true, 1, 0x5) << 0x15) | (fill_nibble<true>(true, 1, 0x6) << 0x16) | (fill_nibble<true>(true, 1, 0x7) << 0x17) |
|
||
(fill_nibble<true>(true, 1, 0x8) << 0x18) | (fill_nibble<true>(true, 1, 0x9) << 0x19) | (fill_nibble<true>(true, 1, 0xa) << 0x1a) | (fill_nibble<true>(true, 1, 0xb) << 0x1b) |
|
||
(fill_nibble<true>(true, 1, 0xc) << 0x1c) | (fill_nibble<true>(true, 1, 0xd) << 0x1d) | (fill_nibble<true>(true, 1, 0xe) << 0x1e) | (fill_nibble<true>(true, 1, 0xf) << 0x1f),
|
||
};
|
||
|
||
constexpr uint32_t fill_values[] = {
|
||
(fill_nibble<false>(false, 0, 0x0) << 0) | (fill_nibble<false>(false, 0, 0x1) << 4) | (fill_nibble<false>(false, 0, 0x2) << 8) | (fill_nibble<false>(false, 0, 0x3) << 12) |
|
||
(fill_nibble<false>(false, 0, 0x4) << 16) | (fill_nibble<false>(false, 0, 0x5) << 20) | (fill_nibble<false>(false, 0, 0x6) << 24) | (fill_nibble<false>(false, 0, 0x7) << 28),
|
||
|
||
(fill_nibble<false>(false, 0, 0x8) << 0) | (fill_nibble<false>(false, 0, 0x9) << 4) | (fill_nibble<false>(false, 0, 0xa) << 8) | (fill_nibble<false>(false, 0, 0xb) << 12) |
|
||
(fill_nibble<false>(false, 0, 0xc) << 16) | (fill_nibble<false>(false, 0, 0xd) << 20) | (fill_nibble<false>(false, 0, 0xe) << 24) | (fill_nibble<false>(false, 0, 0xf) << 28),
|
||
|
||
(fill_nibble<false>(false, 1, 0x0) << 0) | (fill_nibble<false>(false, 1, 0x1) << 4) | (fill_nibble<false>(false, 1, 0x2) << 8) | (fill_nibble<false>(false, 1, 0x3) << 12) |
|
||
(fill_nibble<false>(false, 1, 0x4) << 16) | (fill_nibble<false>(false, 1, 0x5) << 20) | (fill_nibble<false>(false, 1, 0x6) << 24) | (fill_nibble<false>(false, 1, 0x7) << 28),
|
||
|
||
(fill_nibble<false>(false, 1, 0x8) << 0) | (fill_nibble<false>(false, 1, 0x9) << 4) | (fill_nibble<false>(false, 1, 0xa) << 8) | (fill_nibble<false>(false, 1, 0xb) << 12) |
|
||
(fill_nibble<false>(false, 1, 0xc) << 16) | (fill_nibble<false>(false, 1, 0xd) << 20) | (fill_nibble<false>(false, 1, 0xe) << 24) | (fill_nibble<false>(false, 1, 0xf) << 28),
|
||
|
||
(fill_nibble<false>(true, 0, 0x0) << 0) | (fill_nibble<false>(true, 0, 0x1) << 4) | (fill_nibble<false>(true, 0, 0x2) << 8) | (fill_nibble<false>(true, 0, 0x3) << 12) |
|
||
(fill_nibble<false>(true, 0, 0x4) << 16) | (fill_nibble<false>(true, 0, 0x5) << 20) | (fill_nibble<false>(true, 0, 0x6) << 24) | (fill_nibble<false>(true, 0, 0x7) << 28),
|
||
|
||
(fill_nibble<false>(true, 0, 0x8) << 0) | (fill_nibble<false>(true, 0, 0x9) << 4) | (fill_nibble<false>(true, 0, 0xa) << 8) | (fill_nibble<false>(true, 0, 0xb) << 12) |
|
||
(fill_nibble<false>(true, 0, 0xc) << 16) | (fill_nibble<false>(true, 0, 0xd) << 20) | (fill_nibble<false>(true, 0, 0xe) << 24) | (fill_nibble<false>(true, 0, 0xf) << 28),
|
||
|
||
(fill_nibble<false>(true, 1, 0x0) << 0) | (fill_nibble<false>(true, 1, 0x1) << 4) | (fill_nibble<false>(true, 1, 0x2) << 8) | (fill_nibble<false>(true, 1, 0x3) << 12) |
|
||
(fill_nibble<false>(true, 1, 0x4) << 16) | (fill_nibble<false>(true, 1, 0x5) << 20) | (fill_nibble<false>(true, 1, 0x6) << 24) | (fill_nibble<false>(true, 1, 0x7) << 28),
|
||
|
||
(fill_nibble<false>(true, 1, 0x8) << 0) | (fill_nibble<false>(true, 1, 0x9) << 4) | (fill_nibble<false>(true, 1, 0xa) << 8) | (fill_nibble<false>(true, 1, 0xb) << 12) |
|
||
(fill_nibble<false>(true, 1, 0xc) << 16) | (fill_nibble<false>(true, 1, 0xd) << 20) | (fill_nibble<false>(true, 1, 0xe) << 24) | (fill_nibble<false>(true, 1, 0xf) << 28),
|
||
};
|
||
|
||
}
|
||
|
||
void Blitter::set_control(int index, uint16_t value) {
|
||
if(index) {
|
||
line_mode_ = (value & 0x0001);
|
||
one_dot_ = value & 0x0002;
|
||
line_direction_ = (value >> 2) & 7;
|
||
line_sign_ = (value & 0x0040) ? -1 : 1;
|
||
|
||
direction_ = one_dot_ ? uint32_t(-1) : uint32_t(1);
|
||
exclusive_fill_ = (value & 0x0010);
|
||
inclusive_fill_ = !exclusive_fill_ && (value & 0x0008); // Exclusive fill takes precedence. Probably? TODO: verify.
|
||
fill_carry_ = (value & 0x0004);
|
||
} else {
|
||
minterms_ = value & 0xff;
|
||
channel_enables_[3] = value & 0x100;
|
||
channel_enables_[2] = value & 0x200;
|
||
channel_enables_[1] = value & 0x400;
|
||
channel_enables_[0] = value & 0x800;
|
||
}
|
||
shifts_[index] = value >> 12;
|
||
LOG("Set control " << index << " to " << PADHEX(4) << value);
|
||
}
|
||
|
||
void Blitter::set_first_word_mask(uint16_t value) {
|
||
LOG("Set first word mask: " << PADHEX(4) << value);
|
||
a_mask_[0] = value;
|
||
}
|
||
|
||
void Blitter::set_last_word_mask(uint16_t value) {
|
||
LOG("Set last word mask: " << PADHEX(4) << value);
|
||
a_mask_[1] = value;
|
||
}
|
||
|
||
void Blitter::set_size(uint16_t value) {
|
||
// width_ = (width_ & ~0x3f) | (value & 0x3f);
|
||
// height_ = (height_ & ~0x3ff) | (value >> 6);
|
||
width_ = value & 0x3f;
|
||
if(!width_) width_ = 0x40;
|
||
height_ = value >> 6;
|
||
if(!height_) height_ = 1024;
|
||
LOG("Set size to " << std::dec << width_ << ", " << height_);
|
||
|
||
// Current assumption: writing this register informs the
|
||
// blitter that it should treat itself as about to start a new line.
|
||
}
|
||
|
||
void Blitter::set_minterms(uint16_t value) {
|
||
LOG("Set minterms " << PADHEX(4) << value);
|
||
minterms_ = value & 0xff;
|
||
}
|
||
|
||
//void Blitter::set_vertical_size([[maybe_unused]] uint16_t value) {
|
||
// LOG("Set vertical size " << PADHEX(4) << value);
|
||
// // TODO. This is ECS only, I think. Ditto set_horizontal_size.
|
||
//}
|
||
//
|
||
//void Blitter::set_horizontal_size([[maybe_unused]] uint16_t value) {
|
||
// LOG("Set horizontal size " << PADHEX(4) << value);
|
||
//}
|
||
|
||
void Blitter::set_data(int channel, uint16_t value) {
|
||
LOG("Set data " << channel << " to " << PADHEX(4) << value);
|
||
|
||
// Ugh, backed myself into a corner. TODO: clean.
|
||
switch(channel) {
|
||
case 0: a_data_ = value; break;
|
||
case 1: b_data_ = value; break;
|
||
case 2: c_data_ = value; break;
|
||
default: break;
|
||
}
|
||
}
|
||
|
||
uint16_t Blitter::get_status() {
|
||
const uint16_t result =
|
||
(not_zero_flag_ ? 0x0000 : 0x2000) | (height_ ? 0x4000 : 0x0000);
|
||
LOG("Returned status of " << result);
|
||
return result;
|
||
}
|
||
|
||
bool Blitter::advance_dma() {
|
||
if(!height_) return false;
|
||
|
||
not_zero_flag_ = false;
|
||
if(line_mode_) {
|
||
// As-yet unimplemented:
|
||
assert(b_data_ == 0xffff);
|
||
|
||
//
|
||
// Line mode.
|
||
//
|
||
|
||
// Bluffer's guide to line mode:
|
||
//
|
||
// In Bresenham terms, the following registers have been set up:
|
||
//
|
||
// [A modulo] = 4 * (dy - dx)
|
||
// [B modulo] = 4 * dy
|
||
// [A pointer] = 4 * dy - 2 * dx, with the sign flag in BLTCON1 indicating sign.
|
||
//
|
||
// [A data] = 0x8000
|
||
// [Both masks] = 0xffff
|
||
// [A shift] = x1 & 15
|
||
//
|
||
// [B data] = texture
|
||
// [B shift] = bit at which to start the line texture (0 = LSB)
|
||
//
|
||
// [C and D pointers] = word containing the first pixel of the line
|
||
// [C and D modulo] = width of the bitplane in bytes
|
||
//
|
||
// height = number of pixels
|
||
//
|
||
// If ONEDOT of BLTCON1 is set, plot only a single bit per horizontal row.
|
||
//
|
||
// BLTCON1 quadrants are (bits 2–4):
|
||
//
|
||
// 110 -> step in x, x positive, y negative
|
||
// 111 -> step in x, x negative, y negative
|
||
// 101 -> step in x, x negative, y positive
|
||
// 100 -> step in x, x positive, y positive
|
||
//
|
||
// 001 -> step in y, x positive, y negative
|
||
// 011 -> step in y, x negative, y negative
|
||
// 010 -> step in y, x negative, y positive
|
||
// 000 -> step in y, x positive, y positive
|
||
//
|
||
// So that's:
|
||
//
|
||
// * bit 4 = x [=1] or y [=0] major;
|
||
// * bit 3 = 1 => major variable negative; otherwise positive;
|
||
// * bit 2 = 1 => minor variable negative; otherwise positive.
|
||
|
||
//
|
||
// Implementation below is heavily based on the documentation found
|
||
// at https://github.com/niklasekstrom/blitter-subpixel-line/blob/master/Drawing%20lines%20using%20the%20Amiga%20blitter.pdf
|
||
//
|
||
|
||
int error = int16_t(pointer_[0] << 1) >> 1; // TODO: what happens if line_sign_ doesn't agree with this?
|
||
bool draw_ = true;
|
||
while(height_--) {
|
||
|
||
if(draw_) {
|
||
// TODO: patterned lines. Unclear what to do with the bit that comes out of b.
|
||
// Probably extend it to a full word?
|
||
c_data_ = ram_[pointer_[3] & ram_mask_];
|
||
const uint16_t output =
|
||
apply_minterm<uint16_t>(a_data_ >> shifts_[0], b_data_, c_data_, minterms_);
|
||
ram_[pointer_[3] & ram_mask_] = output;
|
||
not_zero_flag_ |= output;
|
||
draw_ &= !one_dot_;
|
||
}
|
||
|
||
constexpr int LEFT = 1 << 0;
|
||
constexpr int RIGHT = 1 << 1;
|
||
constexpr int UP = 1 << 2;
|
||
constexpr int DOWN = 1 << 3;
|
||
int step = (line_direction_ & 4) ?
|
||
((line_direction_ & 1) ? LEFT : RIGHT) :
|
||
((line_direction_ & 1) ? UP : DOWN);
|
||
|
||
if(error < 0) {
|
||
error += modulos_[1];
|
||
} else {
|
||
step |=
|
||
(line_direction_ & 4) ?
|
||
((line_direction_ & 2) ? UP : DOWN) :
|
||
((line_direction_ & 2) ? LEFT : RIGHT);
|
||
|
||
error += modulos_[0];
|
||
}
|
||
|
||
if(step & LEFT) {
|
||
--shifts_[0];
|
||
if(shifts_[0] == -1) {
|
||
--pointer_[3];
|
||
}
|
||
} else if(step & RIGHT) {
|
||
++shifts_[0];
|
||
if(shifts_[0] == 16) {
|
||
++pointer_[3];
|
||
}
|
||
}
|
||
shifts_[0] &= 15;
|
||
|
||
if(step & UP) {
|
||
pointer_[3] -= modulos_[2];
|
||
draw_ = true;
|
||
} else if(step & DOWN) {
|
||
pointer_[3] += modulos_[2];
|
||
draw_ = true;
|
||
}
|
||
}
|
||
} else {
|
||
// Copy mode.
|
||
|
||
// Quick hack: do the entire action atomically.
|
||
a32_ = 0;
|
||
b32_ = 0;
|
||
|
||
for(int y = 0; y < height_; y++) {
|
||
bool fill_carry = fill_carry_;
|
||
|
||
for(int x = 0; x < width_; x++) {
|
||
uint16_t a_mask = 0xffff;
|
||
if(x == 0) a_mask &= a_mask_[0];
|
||
if(x == width_ - 1) a_mask &= a_mask_[1];
|
||
|
||
if(channel_enables_[0]) {
|
||
a_data_ = ram_[pointer_[0] & ram_mask_];
|
||
pointer_[0] += direction_;
|
||
}
|
||
a32_ = (a32_ << 16) | (a_data_ & a_mask);
|
||
|
||
if(channel_enables_[1]) {
|
||
b_data_ = ram_[pointer_[1] & ram_mask_];
|
||
pointer_[1] += direction_;
|
||
}
|
||
b32_ = (b32_ << 16) | b_data_;
|
||
|
||
if(channel_enables_[2]) {
|
||
c_data_ = ram_[pointer_[2] & ram_mask_];
|
||
pointer_[2] += direction_;
|
||
}
|
||
|
||
uint16_t a, b;
|
||
|
||
// The barrel shifter shifts to the right in ascending address mode,
|
||
// but to the left otherwise
|
||
if(!one_dot_) {
|
||
a = uint16_t(a32_ >> shifts_[0]);
|
||
b = uint16_t(b32_ >> shifts_[1]);
|
||
} else {
|
||
// TODO: there must be a neater solution than this.
|
||
a = uint16_t(
|
||
(a32_ << shifts_[0]) |
|
||
(a32_ >> (32 - shifts_[0]))
|
||
);
|
||
|
||
b = uint16_t(
|
||
(b32_ << shifts_[1]) |
|
||
(b32_ >> (32 - shifts_[1]))
|
||
);
|
||
}
|
||
|
||
uint16_t output =
|
||
apply_minterm<uint16_t>(
|
||
a,
|
||
b,
|
||
c_data_,
|
||
minterms_);
|
||
|
||
if(exclusive_fill_ || inclusive_fill_) {
|
||
// Use the fill tables nibble-by-nibble to figure out the filled word.
|
||
uint16_t fill_output = 0;
|
||
int ongoing_carry = fill_carry;
|
||
const int type_mask = exclusive_fill_ ? (1 << 5) : 0;
|
||
for(int c = 0; c < 16; c += 4) {
|
||
const int total_index = (output & 0xf) | (ongoing_carry << 4) | type_mask;
|
||
fill_output |= ((fill_values[total_index >> 3] >> ((total_index & 7) * 4)) & 0xf) << c;
|
||
ongoing_carry = (fill_carries[total_index >> 5] >> (total_index & 31)) & 1;
|
||
output >>= 4;
|
||
}
|
||
|
||
output = fill_output;
|
||
fill_carry = ongoing_carry;
|
||
}
|
||
|
||
not_zero_flag_ |= output;
|
||
|
||
if(channel_enables_[3]) {
|
||
ram_[pointer_[3] & ram_mask_] = output;
|
||
pointer_[3] += direction_;
|
||
}
|
||
}
|
||
|
||
pointer_[0] += modulos_[0] * channel_enables_[0] * direction_;
|
||
pointer_[1] += modulos_[1] * channel_enables_[1] * direction_;
|
||
pointer_[2] += modulos_[2] * channel_enables_[2] * direction_;
|
||
pointer_[3] += modulos_[3] * channel_enables_[3] * direction_;
|
||
}
|
||
}
|
||
|
||
posit_interrupt(InterruptFlag::Blitter);
|
||
height_ = 0;
|
||
|
||
return true;
|
||
}
|