Exercise $6\mathrm{.}18$ Consider the RISC$-$V assembly code below. func$1,$ func$2,$ and func $3$ are nonleaf functions. func $4$ is a leaf function. The code is not shown for each function, but the comments indicate which registers are used within each function. You may assume that the functions do not need to save any nonpreserved registers on their stacks.

$0$x$00091000$ func$1$: $...$ func$1$ uses t$2-$t$3,$ s$4-$s$10$

$...$

$0$x$00091020$ jal func$2$

$...$

$0$x$00091100$ func$2$: $...$ func$2$ uses a$0-$a$2,$ s$0-$s$5$

$..$

$0$x$0009117$ jal func$3$

$...$

$0$x$00091400$ func$3$:$...$ func$3$ uses t$3,$ s$7-$s$9$

$...$

$0$x$00091704$ jal func$4$

$...$

$0$x$00093008$ func$4$:$...$ func$4$ uses s$10-$s$12$

$...$

$0$x$00093118$ jr ra

$($a$)$ How many words are the stack frames of each function?

$($b$)$ Sketch the stack after func$4$ is called. Clearly indicate which registers are stored where on the stack and mark each of the stack frames. Give values where possible. Assume that $sp=0$ABC$124$ just before func$1$ is called.