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Name some magic constants; use std::copy.

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This commit is contained in:
Thomas Harte
2025-12-05 14:28:07 -05:00
parent 2e67f19726
commit 9c42a70635
1 changed files with 19 additions and 8 deletions
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Machines/Commodore/Plus4/TapeHandler.hpp
+19 -8
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@@ -123,6 +123,13 @@ struct TapeHandler: public ClockingHint::Observer {
template <typename M6502T>
bool perform_ldcass(M6502T &m6502, std::array<uint8_t, 65536> &ram, const Cycles timer_cycle_length) {
// Magic constants.
static constexpr uint16_t FileNameLength = 0xab;
static constexpr uint16_t FileNameAddress = 0xaf;
static constexpr uint16_t TapeBlockType = 0xf8;
static constexpr uint16_t SecondAddressFlag = 0xad;
static constexpr uint16_t HeaderBuffer = 0x0333;
// Imply an automatic motor start.
play_button_ = true;
update_tape_motor();
@@ -140,9 +147,9 @@ struct TapeHandler: public ClockingHint::Observer {
// Check for a filename.
std::vector<uint8_t> raw_name;
const uint8_t name_length = ram[0xab];
const uint8_t name_length = ram[FileNameLength];
if(name_length) {
const uint16_t address = uint16_t(ram[0xaf] | (ram[0xb0] << 8));
const uint16_t address = uint16_t(ram[FileNameAddress] | (ram[FileNameAddress + 1] << 8));
for(uint16_t c = 0; c < name_length; c++) {
raw_name.push_back(ram[address + c]);
}
@@ -157,24 +164,28 @@ struct TapeHandler: public ClockingHint::Observer {
if(body && body->parity_was_valid) {
// Copy header into place.
header->serialise(&ram[0x0333], 65536 - 0x0333);
header->serialise(&ram[HeaderBuffer], uint16_t(ram.size() - HeaderBuffer));
// Set block type; 0x00 = data body.
ram[0xf8] = 0;
ram[TapeBlockType] = 0;
// TODO: F5 = checksum.
auto load_address =
ram[0xad] ? header->starting_address : uint16_t((registers.y << 8) | registers.x);
ram[SecondAddressFlag] ? header->starting_address : uint16_t((registers.y << 8) | registers.x);
// Set 'load ram base', 'sta' and 'tapebs'.
ram[0xb2] = ram[0xb4] = ram[0xb6] = load_address & 0xff;
ram[0xb3] = ram[0xb5] = ram[0xb7] = load_address >> 8;
for(const auto byte: body->data) {
ram[load_address] = byte;
++load_address;
if(load_address + body->data.size() < 65536) {
std::copy(body->data.begin(), body->data.end(), &ram[load_address]);
} else {
const auto split_point = body->data.begin() + 65536 - load_address;
std::copy(body->data.begin(), split_point, &ram[load_address]);
std::copy(split_point, body->data.end(), &ram[0]);
}
load_address += body->data.size();
// Set final tape byte.
ram[0xa7] = body->data.back();