Quiz 3 of Computer Architecture (2024 Fall)

:information_source: General Information

• You are allowed to read lecture materials and run RISC-V code inside the Ripes simulator.

  That is, an open book exam.

• We are using the honor system during this quiz, and would like you to accept the following:
  1. You will not share the quiz with anyone.
  2. You will not discuss the material on the quiz with anyone until after solutions are released.
• Download the PDF document at the bottom of this page, which contains the problem set for Quiz 3. You will be prompted to enter a password. Ensure that you have read the notice at the end of this page.
• Each answer has 5 points.
• You must answer in valid numeric representation and/or English alphabet except your formal name.
• Always provide your answer in the shortest form. For example, use ptr->member instead of (*ptr).member.
• Assume that each C program already includes the headers <stdint.h>, <stdbool.h>, <stddef.h>, <stdlib.h>, and <stdio.h>.
• The C standard referenced in this quiz is C99, officially known as ISO/IEC 9899:2018.
• Message the instructor via Facebook if you found something wrong.
• :timer_clock: 09:10 ~ 10:30AM on Oct 22, 2024

Problem set for Quiz 3

$\to$ The password for the PDF document is the most frequent RISC-V instruction displayed by rv32emu's instruction histogram tool. Use lowercase letters.

Correction

• Problem A

static uint32_t ram_load16(ram_t *mem, uint32_t addr)
{
    size_t index = addr - RAM_BASE;
    return ((uint32_t) mem->mem[index] | ((uint32_t) mem->mem[index + 1] << 8));
}

static uint32_t ram_load32(ram_t *mem, uint32_t addr)
{
    size_t index = addr - RAM_BASE;
    return ((uint32_t) mem->mem[index] | ((uint32_t) mem->mem[index + 1] << 8) |
            ((uint32_t) mem->mem[index + 2] << 16) |
            ((uint32_t) mem->mem[index + 3] << 24));
}

• Problem C

// Lookup table for reciprocal square root approximations.
rsqrtapp:   
    .byte   0xf1, 0xda, 0xc9, 0xbb, 0xb0, 0xa6, 0x9e, 0x97, 0x91, 0x8b, 0x86, 0x82