- * int binary = BcdConversion.bcdToBinary(0x1234);
- * System.out.println("BCD 0x1234 to binary: " + binary); // Output: 1234
+ * int decimal = BcdConversion.bcdToDecimal(0x1234);
+ * System.out.println("BCD 0x1234 to decimal: " + decimal); // Output: 1234
*
- * int bcd = BcdConversion.binaryToBcd(1234);
- * System.out.println("Binary 1234 to BCD: " + Integer.toHexString(bcd)); // Output: 0x1234
+ * int bcd = BcdConversion.decimalToBcd(1234);
+ * System.out.println("Decimal 1234 to BCD: " + Integer.toHexString(bcd)); // Output: 0x1234
*
*/
public final class BcdConversion {
private BcdConversion() {
}
+
/**
- * Converts a BCD (Binary-Coded Decimal) number to binary.
+ * Converts a BCD (Binary-Coded Decimal) number to a decimal number.
+ * Steps: + *
1. Validate the BCD number to ensure all digits are between 0 and 9. + *
2. Extract the last 4 bits (one BCD digit) from the BCD number. + *
3. Multiply the extracted digit by the corresponding power of 10 and add it to the decimal number. + *
4. Shift the BCD number right by 4 bits to process the next BCD digit. + *
5. Repeat steps 1-4 until the BCD number is zero. * * @param bcd The BCD number. - * @return The corresponding binary number. + * @return The corresponding decimal number. + * @throws IllegalArgumentException if the BCD number contains invalid digits. */ - public static int bcdToBinary(int bcd) { - int binary = 0; + public static int bcdToDecimal(int bcd) { + int decimal = 0; int multiplier = 1; + + // Validate BCD digits while (bcd > 0) { - int digit = bcd & 0xF; // Extract the last 4 bits (one BCD digit) - binary += digit * multiplier; + int digit = bcd & 0xF; + if (digit > 9) { + throw new IllegalArgumentException("Invalid BCD digit: " + digit); + } + decimal += digit * multiplier; multiplier *= 10; - bcd >>= 4; // Shift right by 4 bits to process the next BCD digit + bcd >>= 4; } - return binary; + return decimal; } /** - * Converts a binary number to BCD (Binary-Coded Decimal). + * Converts a decimal number to BCD (Binary-Coded Decimal). + *
Steps: + *
1. Check if the decimal number is within the valid range for BCD (0 to 9999). + *
2. Extract the last decimal digit from the decimal number. + *
3. Shift the digit to the correct BCD position and add it to the BCD number. + *
4. Remove the last decimal digit from the decimal number. + *
5. Repeat steps 2-4 until the decimal number is zero. * - * @param binary The binary number. + * @param decimal The decimal number. * @return The corresponding BCD number. + * @throws IllegalArgumentException if the decimal number is greater than 9999. */ - public static int binaryToBcd(int binary) { + public static int decimalToBcd(int decimal) { + if (decimal < 0 || decimal > 9999) { + throw new IllegalArgumentException("Value out of bounds for BCD representation: " + decimal); + } + int bcd = 0; int shift = 0; - while (binary > 0) { - int digit = binary % 10; // Extract the last decimal digit - bcd |= (digit << (shift * 4)); // Shift the digit to the correct BCD position - binary /= 10; // Remove the last decimal digit + while (decimal > 0) { + int digit = decimal % 10; + bcd |= (digit << (shift * 4)); + decimal /= 10; shift++; } return bcd; diff --git a/src/test/java/com/thealgorithms/bitmanipulation/BcdConversionTest.java b/src/test/java/com/thealgorithms/bitmanipulation/BcdConversionTest.java index 85221d92a..727b07eb9 100644 --- a/src/test/java/com/thealgorithms/bitmanipulation/BcdConversionTest.java +++ b/src/test/java/com/thealgorithms/bitmanipulation/BcdConversionTest.java @@ -1,65 +1,85 @@ package com.thealgorithms.bitmanipulation; import static org.junit.jupiter.api.Assertions.assertEquals; +import static org.junit.jupiter.api.Assertions.assertThrows; import org.junit.jupiter.api.Test; -/** - * Unit tests for the BcdConversion class. - */ public class BcdConversionTest { - /** - * Test the bcdToBinary method with a BCD number. - */ @Test - public void testBcdToBinary() { - int binary = BcdConversion.bcdToBinary(0x1234); - assertEquals(1234, binary); // BCD 0x1234 should convert to binary 1234 + public void testBcdToDecimal() { + int decimal = BcdConversion.bcdToDecimal(0x1234); + assertEquals(1234, decimal); // BCD 0x1234 should convert to decimal 1234 } - /** - * Test the binaryToBcd method with a binary number. - */ @Test - public void testBinaryToBcd() { - int bcd = BcdConversion.binaryToBcd(1234); - assertEquals(0x1234, bcd); // Binary 1234 should convert to BCD 0x1234 + public void testDecimalToBcd() { + int bcd = BcdConversion.decimalToBcd(1234); + assertEquals(0x1234, bcd); // Decimal 1234 should convert to BCD 0x1234 } - /** - * Test the bcdToBinary method with zero. - */ @Test - public void testBcdToBinaryZero() { - int binary = BcdConversion.bcdToBinary(0x0); - assertEquals(0, binary); // BCD 0x0 should convert to binary 0 + public void testBcdToDecimalZero() { + int decimal = BcdConversion.bcdToDecimal(0x0); + assertEquals(0, decimal); // BCD 0x0 should convert to decimal 0 } - /** - * Test the binaryToBcd method with zero. - */ @Test - public void testBinaryToBcdZero() { - int bcd = BcdConversion.binaryToBcd(0); - assertEquals(0x0, bcd); // Binary 0 should convert to BCD 0x0 + public void testDecimalToBcdZero() { + int bcd = BcdConversion.decimalToBcd(0); + assertEquals(0x0, bcd); // Decimal 0 should convert to BCD 0x0 } - /** - * Test the bcdToBinary method with a single digit BCD number. - */ @Test - public void testBcdToBinarySingleDigit() { - int binary = BcdConversion.bcdToBinary(0x7); - assertEquals(7, binary); // BCD 0x7 should convert to binary 7 + public void testBcdToDecimalSingleDigit() { + int decimal = BcdConversion.bcdToDecimal(0x7); + assertEquals(7, decimal); // BCD 0x7 should convert to decimal 7 } - /** - * Test the binaryToBcd method with a single digit binary number. - */ @Test - public void testBinaryToBcdSingleDigit() { - int bcd = BcdConversion.binaryToBcd(7); - assertEquals(0x7, bcd); // Binary 7 should convert to BCD 0x7 + public void testDecimalToBcdSingleDigit() { + int bcd = BcdConversion.decimalToBcd(7); + assertEquals(0x7, bcd); // Decimal 7 should convert to BCD 0x7 + } + + @Test + public void testBcdToDecimalMaxValue() { + int decimal = BcdConversion.bcdToDecimal(0x9999); + assertEquals(9999, decimal); // BCD 0x9999 should convert to decimal 9999 + } + + @Test + public void testDecimalToBcdMaxValue() { + int bcd = BcdConversion.decimalToBcd(9999); + assertEquals(0x9999, bcd); // Decimal 9999 should convert to BCD 0x9999 + } + + @Test + public void testBcdToDecimalInvalidHighDigit() { + // Testing invalid BCD input where one of the digits is > 9 + assertThrows(IllegalArgumentException.class, () -> { + BcdConversion.bcdToDecimal(0x123A); // Invalid BCD, 'A' is not a valid digit + }); + } + + @Test + public void testDecimalToBcdInvalidValue() { + // Testing conversion for numbers greater than 9999, which cannot be represented in BCD + assertThrows(IllegalArgumentException.class, () -> { + BcdConversion.decimalToBcd(10000); // 10000 is too large for BCD representation + }); + } + + @Test + public void testBcdToDecimalLeadingZeroes() { + int decimal = BcdConversion.bcdToDecimal(0x0234); + assertEquals(234, decimal); // BCD 0x0234 should convert to decimal 234, ignoring leading zero + } + + @Test + public void testDecimalToBcdLeadingZeroes() { + int bcd = BcdConversion.decimalToBcd(234); + assertEquals(0x0234, bcd); // Decimal 234 should convert to BCD 0x0234 } }