Question

Write a subroutine to swap the first row of a matrix MAT with the last row, the second row with the second-to-last row, etc. The matrix MAT is NxM and is stored in row-major order. The starting address of MAT and its dimensions (N and M) are passed to this subroutine in the stack in this order: matrix base address, N, and M (that is, the matrix base address is pushed onto the stack first, followed by N and M). The matrix elements are 8-bit.

Answer 1

The question is about creating a subroutine to swap corresponding rows of a matrix, addressed in a low-level programming context, involving careful manipulation of data in memory.

Step-by-step explanation:

The subject of this question is related to writing a subroutine in a low-level or assembly language. Specifically, it involves swapping rows in a matrix that is stored in row-major order. The dimensions and the starting address of the matrix are passed through the stack. This subroutine requires understanding of pointers or indexed addressing, loops, and the layout of data in memory.

To swap the rows, one must iterate over half the number of rows (since each swap affects two rows) and perform an element-wise swap for each column within those rows. Due care must be taken to ensure that the swap is performed correctly when the matrix has an odd number of rows since the middle row does not need to be swapped.