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amejiarosarioamejiarosario
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5.8 initial solution
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6 files changed

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‎src/05-bits/00-bit-manipulation.js‎

Lines changed: 17 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -54,9 +54,25 @@ function updateBit2(n, i, b) {
5454
return (n & mask) | (b << i);
5555
}
5656

57+
/**
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* Set number to 1 from start (inclusively) to end (exclusively)
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* @param n number
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* @param start
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* @param end
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* @returns {number}
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*/
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function setBitsRange(n, start = 0, end = 32) {
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if(!(end - start) || start > end || start < 0) { return n; }
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let mask = (~0 >>> (32 - (end - start)));
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if(end - start === 32) { return mask; }
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mask <<= start;
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return n | mask;
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}
71+
5772
module.exports = {
5873
getBit,
5974
setBit,
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clearBit,
61-
updateBit
76+
updateBit,
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setBitsRange
6278
};

‎src/05-bits/00-bit-manipulation.spec.js‎

Lines changed: 38 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -77,4 +77,42 @@ describe('Bit Manipulation', function() {
7777
expect(bm.updateBit(0b1010, 3, 1).toString(2)).to.equal((0b1010).toString(2));
7878
});
7979
});
80+
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describe('setBitsRange', function () {
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it('should have defaults', function () {
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expect(bm.setBitsRange(0).toString(2)).to.equal('11111111111111111111111111111111');
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});
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it('should handle negatives', function () {
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expect(bm.setBitsRange(0, -1, 0).toString(2)).to.equal('0');
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});
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it('should handle start bigger than end', function () {
91+
expect(bm.setBitsRange(0, 10, 1).toString(2)).to.equal('0');
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});
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it('should set 0 to 0', function () {
95+
expect(bm.setBitsRange(0, 0, 0).toString(2)).to.equal('0');
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});
97+
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it('should set 0 to 1', function () {
99+
expect(bm.setBitsRange(0, 0, 1).toString(2)).to.equal('1');
100+
});
101+
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it('should set 0 to 2', function () {
103+
expect(bm.setBitsRange(0, 0, 2).toString(2)).to.equal('11');
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});
105+
106+
it('should set 1 to 4', function () {
107+
expect(bm.setBitsRange(0, 1, 4).toString(2)).to.equal('1110');
108+
});
109+
110+
it('should set 0 to 8', function () {
111+
expect(bm.setBitsRange(0, 0, 8).toString(2)).to.equal('11111111');
112+
});
113+
114+
it('should 1010', function () {
115+
expect(bm.setBitsRange(0b1010, 0, 1).toString(2)).to.equal('1011');
116+
});
117+
});
80118
});

‎src/05-bits/07-pairwise-swap.js‎

Lines changed: 9 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -16,4 +16,13 @@ function pairwiseSwap(number) {
1616
return swapped;
1717
}
1818

19+
/**
20+
* Shift odd numbers one place to the right and then even bits one to the left
21+
* @param number
22+
* @returns {number}
23+
*/
24+
function swapOddEvenBits(number) {
25+
return ((number & 0xaaaaaaaa) >>> 1) | ((number & 0x55555555) << 1)
26+
}
27+
1928
module.exports = pairwiseSwap;

‎src/05-bits/07-pairwise-swap.spec.js‎

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -21,4 +21,8 @@ describe('Bit Manipulation: pairwiseSwap', function() {
2121
it('larger', function() {
2222
expect(pairwiseSwap(0b0110010101)).to.equal(0b1001101010);
2323
});
24+
25+
xit('max safe integer (js)', function () {
26+
expect(pairwiseSwap(Number.MAX_SAFE_INTEGER)).to.equal(Number.MAX_SAFE_INTEGER);
27+
})
2428
});

‎src/05-bits/08-draw-line.js‎

Lines changed: 48 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,48 @@
1+
/**
2+
* 5.8 Draw Line: A monochrome screen is stored as a single array of bytes, allowing eight consecutive pixels to be stored in one byte. The screen has width w, where w is divisible by 8 (that is, no byte will be split across rows).
3+
* The height of the screen, of course, can be derived from the length of the array and the width.Implement a function that draws a horizontal line from (x1, y) to (x2, y).
4+
*
5+
The method signature should look something like:
6+
drawLine(byte[] screen, int width, int xl, int x2, int y)
7+
8+
Hints: #366, #381, #384, #391
9+
*/
10+
11+
const bm = require('./00-bit-manipulation');
12+
13+
/**
14+
*
15+
* @param screen array of bytes
16+
* @param width {integer} in bytes
17+
* @param x1 integer
18+
* @param x2 integer
19+
* @param y integer
20+
*/
21+
function drawLine(screen, width, x1, x2, y){
22+
// validations
23+
if(x2 <= x1 || x1 < 0) { return screen; }
24+
25+
const i1 = y * screen.length/(width/8) + parseInt(x1/8);
26+
const i2 = y * screen.length/(width/8) + parseInt((x2 - 1)/8);
27+
28+
// console.log(i1, i2, screen.length/(width/8));
29+
30+
for(let i = i1; i <= i2; i++) {
31+
if(i1 === i2) {
32+
screen[i] = bm.setBitsRange(screen[i], (8 - x2 % 9), (8 - x1 % 8));
33+
} else if (i === i1) {
34+
screen[i] = bm.setBitsRange(screen[i], 0, (8 - x1 % 8));
35+
// console.log(i, screen[i], 0, (8 - x1));
36+
} else if (i === i2) {
37+
screen[i] = bm.setBitsRange(screen[i], (8 - x2 % 8), 8);
38+
// console.log(i, screen[i], (8 - x2 % 8), 8);
39+
} else {
40+
screen[i] = bm.setBitsRange(screen[i], 0, 8);
41+
// console.log(i, screen[i], 0, 8);
42+
}
43+
}
44+
45+
return screen;
46+
}
47+
48+
module.exports = drawLine;

‎src/05-bits/08-draw-line.spec.js‎

Lines changed: 185 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,185 @@
1+
const expect = require('chai').expect;
2+
const drawLine = require('./08-draw-line');
3+
4+
describe('Bit Manipulation: drawLine', function() {
5+
6+
it('0', function() {
7+
const screen = [0x0];
8+
const width = 8;
9+
const x1 = 0;
10+
const x2 = 0;
11+
const y = 0;
12+
13+
expect(drawLine(screen, width, x1, x2, y)).to.eql([
14+
0b00000000
15+
]);
16+
});
17+
18+
it('1', function() {
19+
const screen = [0x0];
20+
const width = 8;
21+
const x1 = 0;
22+
const x2 = 1;
23+
const y = 0;
24+
25+
expect(drawLine(screen, width, x1, x2, y)).to.eql([
26+
0b10000000
27+
]);
28+
});
29+
30+
it('3', function() {
31+
const screen = [0x0];
32+
const width = 8;
33+
const x1 = 0;
34+
const x2 = 3;
35+
const y = 0;
36+
37+
expect(drawLine(screen, width, x1, x2, y)).to.eql([
38+
0b11100000
39+
]);
40+
});
41+
42+
it('7', function() {
43+
const screen = [0x0];
44+
const width = 8;
45+
const x1 = 0;
46+
const x2 = 7;
47+
const y = 0;
48+
49+
expect(drawLine(screen, width, x1, x2, y)).to.eql([
50+
0b11111110
51+
]);
52+
});
53+
54+
it('8 - all', function() {
55+
const screen = [0x0];
56+
const width = 8;
57+
const x1 = 0;
58+
const x2 = 8;
59+
const y = 0;
60+
61+
expect(drawLine(screen, width, x1, x2, y)).to.eql([
62+
0b11111111
63+
]);
64+
});
65+
66+
it('7-8', function() {
67+
const screen = [0x0];
68+
const width = 8;
69+
const x1 = 7;
70+
const x2 = 8;
71+
const y = 0;
72+
73+
expect(drawLine(screen, width, x1, x2, y)).to.eql([
74+
0b00000001
75+
]);
76+
});
77+
78+
it('center', function() {
79+
const screen = [0x0];
80+
const width = 8;
81+
const x1 = 3;
82+
const x2 = 5;
83+
const y = 0;
84+
85+
expect(drawLine(screen, width, x1, x2, y)[0].toString(2)).to.equal('11000');
86+
});
87+
88+
it('6', function() {
89+
const screen = [0x0];
90+
const width = 8;
91+
const x1 = 6;
92+
const x2 = 8;
93+
const y = 0;
94+
95+
expect(drawLine(screen, width, x1, x2, y)).to.eql([
96+
0b00000011
97+
]);
98+
});
99+
100+
it('12 (5)', function() {
101+
const screen = [0x0];
102+
const width = 8;
103+
const x1 = 0;
104+
const x2 = 4;
105+
const y = 0;
106+
107+
expect(drawLine(screen, width, x1, x2, y)).to.eql([
108+
0b11110000
109+
]);
110+
});
111+
112+
it('2 bytes screen', function() {
113+
const screen = [0x0, 0x0];
114+
const width = 16;
115+
const x1 = 6;
116+
const x2 = 12;
117+
const y = 0;
118+
119+
expect(drawLine(screen, width, x1, x2, y)).to.eql([
120+
0b00000011, 0b11110000
121+
]);
122+
});
123+
124+
it('2x2 screen', function() {
125+
const screen = [0x0, 0x0,
126+
0x0, 0x0];
127+
const width = 16;
128+
const x1 = 6;
129+
const x2 = 12;
130+
const y = 1;
131+
132+
expect(drawLine(screen, width, x1, x2, y)).to.eql([
133+
0b00000000, 0b0000000,
134+
0b00000011, 0b11110000
135+
]);
136+
});
137+
138+
it('3x3 screen interbits', function() {
139+
const screen = [0x0, 0x0, 0x0,
140+
0x0, 0x0, 0x0,
141+
0x0, 0x0, 0x0];
142+
const width = 24;
143+
const x1 = 7;
144+
const x2 = 17;
145+
const y = 1;
146+
147+
expect(drawLine(screen, width, x1, x2, y)).to.eql([
148+
0b00000000, 0b00000000, 0b00000000,
149+
0b00000001, 0b11111111, 0b10000000,
150+
0b00000000, 0b00000000, 0b00000000
151+
]);
152+
});
153+
154+
xit('3x3 screen last byte high', function() {
155+
const screen = [0x0, 0x0, 0x0,
156+
0x0, 0x0, 0x0,
157+
0x0, 0x0, 0x0];
158+
const width = 24;
159+
const x1 = 16;
160+
const x2 = 17;
161+
const y = 2;
162+
163+
expect(drawLine(screen, width, x1, x2, y)).to.eql([
164+
0b00000000, 0b00000000, 0b00000000,
165+
0b00000000, 0b00000000, 0b00000000,
166+
0b00000000, 0b00000000, 0b10000000
167+
]);
168+
});
169+
170+
xit('3x3 screen last byte low', function() {
171+
const screen = [0x0, 0x0, 0x0,
172+
0x0, 0x0, 0x0,
173+
0x0, 0x0, 0x0];
174+
const width = 24;
175+
const x1 = 24;
176+
const x2 = 25;
177+
const y = 2;
178+
179+
expect(drawLine(screen, width, x1, x2, y)).to.eql([
180+
0b00000000, 0b00000000, 0b00000000,
181+
0b00000000, 0b00000000, 0b00000000,
182+
0b00000000, 0b00000000, 0b00000001
183+
]);
184+
});
185+
});

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