32-bit Multiply on 16-bit ALU | Dataford Interview Questions

Write a C program for handling 32-bit multiplication on a microprocessor where ALU supports only 16-bit multiplication

Asked in the Technical 2 stage. The task tests low-level bit manipulation and microprocessor arithmetic constraints. Implement the equivalent Python function below for grading.

Contract

multiply_32bit(a, b) receives two unsigned 32-bit integers and returns their unsigned 64-bit product. Split each operand into two 16-bit halves, use only 16-bit-by-16-bit multiplications, and propagate carries explicitly.

Constraints

0 <= a, b <= 2^32 - 1
The returned product fits in an unsigned 64-bit integer.
Only 16-bit-by-16-bit multiplication operations may be used.
Use explicit masking, shifting, and carry propagation to combine partial products.

Function Signature

def multiply_32bit(a, b):

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Problem