HSCOD - Exercise - Cache Design

hscod-exercise-cache-design.js

const spacer = '--------------------------------------------------';
const decToBin = (dec, paddingCount = 8) =>
  dec.toString(2).padStart(paddingCount, '0');

console.log(`${spacer}\nExercise 1\n${spacer}`);
{
  const addressSize = 8;
  const addressReferences = [3, 180, 43, 2, 191, 88, 190, 2, 88];
  const indexes = {};

  console.log('REF - BIN        - TAG    - INDEX  - CACHE');
  addressReferences.forEach(ref => {
    const decStr = ref.toString().padStart(3, ' ');
    const refStr = decToBin(ref, addressSize);
    const index = decToBin(ref % 16, 4);
    const tag = decToBin((ref & ~16) >> 4, 4);
    const hit = indexes[index] === tag ? 'HIT' : 'MISS';
    indexes[index] = tag;
    console.log(`${decStr} - 0b${refStr} - 0b${tag} - 0b${index} - ${hit}`);
  });
}

console.log(`${spacer}\nExercise 2\n${spacer}`);
{
  const addressSize = 32;
  const offsetLength = 5 - 0 + 1;
  const indexLenth = 11 - 6 + 1;
  const tagLength = 31 - 12 + 1;
  const addressReferences = [
    0,
    4,
    16,
    132,
    232,
    160,
    1024,
    30,
    140,
    3100,
    180,
    2180
  ];
  const indexes = {};
  let hits = 0;

  console.log(`ASSUMPTION: BLOCK OFFSET AND 8 BIT WORD SIZE`);
  console.log(`A: CACHE LINE SIZE:   ${2 ** offsetLength} WORDS`);
  console.log(`B: CACHE BLOCK COUNT: ${2 ** indexLenth} BLOCKS`);

  console.log(
    'C: REF  - BIN                                - TAG                    - INDEX    - OFFSET   - CACHE - START - END'
  );
  addressReferences.forEach(ref => {
    const decStr = ref.toString().padStart(7, ' ');
    const refStr = decToBin(ref, addressSize);
    const offset = decToBin(ref % 64, offsetLength);
    const index = decToBin((ref & (63 << 6)) >> 6, indexLenth);
    const tag = decToBin((ref & (~63 << 6)) >> 6, tagLength);
    const dataStart = ref & ~63;
    const dataEnd = dataStart + 63;
    const dataStartStr = dataStart.toString().padStart(5, ' ');
    const dataEndStr = dataEnd.toString().padStart(5, ' ');
    const hit = indexes[index] && indexes[index].tag === tag ? 'HIT ' : 'MISS';
    if (hit.trim() === 'HIT') {
      ++hits;
    }
    indexes[index] = {
      tag,
      offset,
      dataStart,
      dataEnd
    };
    console.log(
      `${decStr} - 0b${refStr} - 0b${tag} - 0b${index} - 0b${offset} - ${hit}  - ${dataStartStr} - ${dataEndStr}`
    );
  });
  console.log(`   TOTAL HITS: ${hits}`);
  console.log(
    `   HITRATE:    ${Math.round((hits / addressReferences.length) * 100)}%`
  );
}

The result is:

--------------------------------------------------
Exercise 1
--------------------------------------------------
REF - BIN        - TAG    - INDEX  - CACHE
  3 - 0b00000011 - 0b0000 - 0b0011 - MISS
180 - 0b10110100 - 0b1010 - 0b0100 - MISS
 43 - 0b00101011 - 0b0010 - 0b1011 - MISS
  2 - 0b00000010 - 0b0000 - 0b0010 - MISS
191 - 0b10111111 - 0b1010 - 0b1111 - MISS
 88 - 0b01011000 - 0b0100 - 0b1000 - MISS
190 - 0b10111110 - 0b1010 - 0b1110 - MISS
  2 - 0b00000010 - 0b0000 - 0b0010 - HIT
 88 - 0b01011000 - 0b0100 - 0b1000 - HIT
--------------------------------------------------
Exercise 2
--------------------------------------------------
ASSUMPTION: BLOCK OFFSET AND 8 BIT WORD SIZE
A: CACHE LINE SIZE:   64 WORDS
B: CACHE BLOCK COUNT: 64 BLOCKS
C: REF  - BIN                                - TAG                    - INDEX    - OFFSET   - CACHE - START - END
      0 - 0b00000000000000000000000000000000 - 0b00000000000000000000 - 0b000000 - 0b000000 - MISS  -     0 -    63
      4 - 0b00000000000000000000000000000100 - 0b00000000000000000000 - 0b000000 - 0b000100 - HIT   -     0 -    63
     16 - 0b00000000000000000000000000010000 - 0b00000000000000000000 - 0b000000 - 0b010000 - HIT   -     0 -    63
    132 - 0b00000000000000000000000010000100 - 0b00000000000000000000 - 0b000010 - 0b000100 - MISS  -   128 -   191
    232 - 0b00000000000000000000000011101000 - 0b00000000000000000000 - 0b000011 - 0b101000 - MISS  -   192 -   255
    160 - 0b00000000000000000000000010100000 - 0b00000000000000000000 - 0b000010 - 0b100000 - HIT   -   128 -   191
   1024 - 0b00000000000000000000010000000000 - 0b00000000000000000000 - 0b010000 - 0b000000 - MISS  -  1024 -  1087
     30 - 0b00000000000000000000000000011110 - 0b00000000000000000000 - 0b000000 - 0b011110 - HIT   -     0 -    63
    140 - 0b00000000000000000000000010001100 - 0b00000000000000000000 - 0b000010 - 0b001100 - HIT   -   128 -   191
   3100 - 0b00000000000000000000110000011100 - 0b00000000000000000000 - 0b110000 - 0b011100 - MISS  -  3072 -  3135
    180 - 0b00000000000000000000000010110100 - 0b00000000000000000000 - 0b000010 - 0b110100 - HIT   -   128 -   191
   2180 - 0b00000000000000000000100010000100 - 0b00000000000000000000 - 0b100010 - 0b000100 - MISS  -  2176 -  2239
   TOTAL HITS: 6
   HITRATE:    50%