Homework 7 - Macros/Bit Manipulation

• Assignment
• Macro Requirements
• Turn In
• Hints

Assignment

1. Input a 32-bit decimal number,
2. Reverse the number using a macro that reverses the bits in a 32-bit value. Use bit manipulation instructions of Chapter 6.
3. Output the reversed value,
4. Reverse the reversed value,
5. Output the reversed reversed value. Because reverse is its own inverse, this provides a test that the reverse macro is working correctly.

Macro Requirements

• Save and restore any registers indirectly changed by code in a macro.
• If no actual parameter is supplied the macro should display an error message to the console.
• When labels are used inside a macro definition, ensure that each invocation of the macro produces unique labels (i.e. use local operative).

Turn In

1. Cover page - Your name, date, and Homework 7.
2. Assembler program - Well documented copy of the Hw7.asm file,
3. Assembler listing - HW7.lst printed in landscape mode.
4. Program output - Test using the values: 1, 2147483647, 1073741824, -1.

Hints

• Isolate a single bit at a time and place in the result:
  • An easy method is to rotate or shift the input value one bit, the one bit is in the carry flag.
  • Rotate the carry flag into the result, rotating in the opposite direction the input value is rotated or shifted.
• Write out an algorithm by hand before using the computer.

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