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CLK/OSBindings/Mac/Clock SignalTests/MintermTests.mm
2021-10-16 05:37:46 -07:00

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//
// MintermTests.m
// Clock SignalTests
//
// Created by Thomas Harte on 20/09/2021.
// Copyright © 2021 Thomas Harte. All rights reserved.
//
#import <XCTest/XCTest.h>
#include <cstdint>
#include "Minterms.hpp"
namespace {
/// Implements the Amiga minterm algorithm in a bit-by-bit form.
template <typename IntT> IntT slow_minterm(IntT a, IntT b, IntT c, uint8_t minterm) {
constexpr int top_shift = sizeof(IntT) * 8 - 1;
IntT result = 0;
for(int i = 0; i < 8*sizeof(IntT); i++) {
int index = ((c&1) << 0) | ((b&1) << 1) | ((a&1) << 2);
result >>= 1;
result |= ((minterm >> index) & 1) << top_shift;
a >>= 1;
b >>= 1;
c >>= 1;
}
return result;
}
}
@interface MintermTests: XCTestCase
@end
@implementation MintermTests
- (void)testAll {
// These three are selected just to ensure that all combinations of
// bit pattern exist in the input.
constexpr uint8_t a = 0xaa;
constexpr uint8_t b = 0xcc;
constexpr uint8_t c = 0xf0;
for(int minterm = 0; minterm < 256; minterm++) {
const uint8_t slow = slow_minterm(a, b, c, minterm);
const uint8_t fast = Amiga::apply_minterm(a, b, c, minterm);
XCTAssertEqual(slow, fast, "Mismatch found between naive and fast implementations for %02x", minterm);
}
}
@end