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Takes a stab at implementing device response.

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This commit is contained in:
Thomas Harte 2021-02-12 18:56:43 -05:00
parent adfdfa205f
commit ea40b2c982
2 changed files with 40 additions and 2 deletions
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38
Machines/Apple/ADB/ReactiveDevice.cpp
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@ -10,12 +10,46 @@
using namespace Apple::ADB;
ReactiveDevice::ReactiveDevice(Apple::ADB::Bus &bus) : device_id_(bus.add_device(this)) {}
ReactiveDevice::ReactiveDevice(Apple::ADB::Bus &bus) : bus_(bus), device_id_(bus.add_device(this)) {}
void ReactiveDevice::post_response(const std::vector<uint8_t> &&response) {
response_ = std::move(response);
microseconds_at_bit_ = 0.0;
bit_offset_ = -1;
}
void ReactiveDevice::advance_state(double microseconds) {
(void)microseconds;
// Do nothing if not in the process of posting a response.
if(response_.empty()) return;
// Otherwise advance time appropriately.
microseconds_at_bit_ += microseconds;
// Bit '-1' is the sync signal.
if(bit_offset_ == -1) {
bus_.set_device_output(device_id_, false);
if(microseconds_at_bit_ < 300) {
return;
}
microseconds_at_bit_ -= 300;
++bit_offset_;
}
// Advance the implied number of bits.
bit_offset_ += int(microseconds_at_bit_ / 100);
microseconds_at_bit_ -= double(bit_offset_ * 100.0);
// Check for end-of-transmission.
if(bit_offset_ >= int(response_.size() * 10)) {
bus_.set_device_output(device_id_, true);
response_.clear();
return;
}
// Otherwise pick an output level.
const int byte = bit_offset_ / 10;
const int bit = ((0x200 | (int(response_[size_t(byte)]) << 1)) >> (bit_offset_ % 10)) & 1;
constexpr double low_periods[] = {66, 33};
bus_.set_device_output(device_id_, microseconds_at_bit_ > low_periods[bit]);
}

4
Machines/Apple/ADB/ReactiveDevice.hpp
View File

@ -25,8 +25,12 @@ class ReactiveDevice: public Bus::Device {
void advance_state(double microseconds) override;
private:
Bus &bus_;
const size_t device_id_;
std::vector<uint8_t> response_;
int bit_offset_ = 0;
double microseconds_at_bit_ = 0;
};
}