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Add sieve exercise (#283)
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‎config.json

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"transforming"
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]
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},
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{
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"slug": "sieve",
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"name": "Sieve",
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"uuid": "6cc147ff-65cb-417d-9883-6b7cf910e828",
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"practices": [],
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"prerequisites": [],
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"difficulty": 5
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},
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{
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"slug": "space-age",
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"name": "Space Age",

‎exercises/practice/sieve/.docs/instructions.md

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# Instructions
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Your task is to create a program that implements the Sieve of Eratosthenes algorithm to find all prime numbers less than or equal to a given number.
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A prime number is a number larger than 1 that is only divisible by 1 and itself.
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For example, 2, 3, 5, 7, 11, and 13 are prime numbers.
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By contrast, 6 is _not_ a prime number as it not only divisible by 1 and itself, but also by 2 and 3.
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To use the Sieve of Eratosthenes, first, write out all the numbers from 2 up to and including your given number.
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Then, follow these steps:
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1. Find the next unmarked number (skipping over marked numbers).
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This is a prime number.
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2. Mark all the multiples of that prime number as **not** prime.
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Repeat the steps until you've gone through every number.
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At the end, all the unmarked numbers are prime.
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~~~~exercism/note
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The Sieve of Eratosthenes marks off multiples of each prime using addition (repeatedly adding the prime) or multiplication (directly computing its multiples), rather than checking each number for divisibility.
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The tests don't check that you've implemented the algorithm, only that you've come up with the correct primes.
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~~~~
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## Example
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Let's say you're finding the primes less than or equal to 10.
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- Write out 2, 3, 4, 5, 6, 7, 8, 9, 10, leaving them all unmarked.
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```text
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2 3 4 5 6 7 8 9 10
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```
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- 2 is unmarked and is therefore a prime.
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Mark 4, 6, 8 and 10 as "not prime".
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```text
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2 3 [4] 5 [6] 7 [8] 9 [10]
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↑
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```
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- 3 is unmarked and is therefore a prime.
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Mark 6 and 9 as not prime _(marking 6 is optional - as it's already been marked)_.
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```text
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2 3 [4] 5 [6] 7 [8] [9] [10]
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↑
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```
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- 4 is marked as "not prime", so we skip over it.
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```text
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2 3 [4] 5 [6] 7 [8] [9] [10]
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↑
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```
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- 5 is unmarked and is therefore a prime.
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Mark 10 as not prime _(optional - as it's already been marked)_.
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```text
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2 3 [4] 5 [6] 7 [8] [9] [10]
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↑
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```
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- 6 is marked as "not prime", so we skip over it.
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```text
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2 3 [4] 5 [6] 7 [8] [9] [10]
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↑
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```
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- 7 is unmarked and is therefore a prime.
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```text
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2 3 [4] 5 [6] 7 [8] [9] [10]
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↑
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```
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- 8 is marked as "not prime", so we skip over it.
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```text
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2 3 [4] 5 [6] 7 [8] [9] [10]
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↑
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```
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- 9 is marked as "not prime", so we skip over it.
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```text
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2 3 [4] 5 [6] 7 [8] [9] [10]
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↑
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```
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- 10 is marked as "not prime", so we stop as there are no more numbers to check.
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```text
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2 3 [4] 5 [6] 7 [8] [9] [10]
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↑
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```
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You've examined all the numbers and found that 2, 3, 5, and 7 are still unmarked, meaning they're the primes less than or equal to 10.

‎exercises/practice/sieve/.docs/introduction.md

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# Introduction
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You bought a big box of random computer parts at a garage sale.
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You've started putting the parts together to build custom computers.
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You want to test the performance of different combinations of parts, and decide to create your own benchmarking program to see how your computers compare.
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You choose the famous "Sieve of Eratosthenes" algorithm, an ancient algorithm, but one that should push your computers to the limits.

‎exercises/practice/sieve/.meta/config.json

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{
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"authors": [
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"oxe-i"
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],
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"files": {
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"solution": [
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"sieve.asm"
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],
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"test": [
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"sieve_test.c"
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],
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"example": [
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".meta/example.asm"
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]
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},
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"blurb": "Use the Sieve of Eratosthenes to find all the primes from 2 up to a given number.",
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"source": "Sieve of Eratosthenes at Wikipedia",
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"source_url": "https://en.wikipedia.org/wiki/Sieve_of_Eratosthenes"
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}

‎exercises/practice/sieve/.meta/example.asm

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section .text
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global primes
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primes:
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; rdi - output array of uint32_t
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; esi - limit
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; output array should be modified in place
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; the size of array is returned in eax
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xor rax, rax
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cmp esi, 2
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jl sieve_end ; if limit is less than 2 returns right away
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; prologue
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; creates an array of bytes on the stack to represent possible primes
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mov r8d, esi
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inc r8d ; limit is inclusive
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push rbp
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mov rbp, rsp
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sub rsp, r8
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lea rsi, [rsp]
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; sets all bytes to "true"
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mov r10, rdi
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mov rdi, rsi
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mov rcx, r8
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mov al, 1
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cld
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rep stosb
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; loops over the array to get factors
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mov rdi, r10
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mov r11, rsi
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mov rcx, 2 ; current number to check
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xor r9, r9 ; counter for num of primes
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get_primes_loop:
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lodsb
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cmp al, 1
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je store_prime
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next_factor:
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inc rcx
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cmp rcx, r8
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jl get_primes_loop
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; epilogue
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mov rax, r9
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mov rsp, rbp
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pop rbp
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sieve_end:
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ret
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store_prime:
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mov rax, rcx
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stosd
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inc r9
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remove_composites:
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add rax, rcx
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cmp rax, r8
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jge next_factor
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mov byte [r11 + rax - 2], 0
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jmp remove_composites
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%ifidn __OUTPUT_FORMAT__,elf64
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section .note.GNU-stack noalloc noexec nowrite progbits
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%endif

‎exercises/practice/sieve/.meta/tests.toml

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# This is an auto-generated file.
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#
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# Regenerating this file via `configlet sync` will:
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# - Recreate every `description` key/value pair
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# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
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# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
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# - Preserve any other key/value pair
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#
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# As user-added comments (using the # character) will be removed when this file
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# is regenerated, comments can be added via a `comment` key.
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[88529125-c4ce-43cc-bb36-1eb4ddd7b44f]
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description = "no primes under two"
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[4afe9474-c705-4477-9923-840e1024cc2b]
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description = "find first prime"
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[974945d8-8cd9-4f00-9463-7d813c7f17b7]
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description = "find primes up to 10"
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[2e2417b7-3f3a-452a-8594-b9af08af6d82]
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description = "limit is prime"
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[92102a05-4c7c-47de-9ed0-b7d5fcd00f21]
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description = "find primes up to 1000"

‎exercises/practice/sieve/Makefile

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AS = nasm
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CFLAGS = -g -Wall -Wextra -pedantic -Werror
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LDFLAGS =
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ASFLAGS = -g -F dwarf -Werror
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ifeq ($(shell uname -s),Darwin)
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ifeq ($(shell sysctl -n hw.optional.arm64 2>/dev/null),1)
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ALL_CFLAGS = -target x86_64-apple-darwin
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endif
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ALL_LDFLAGS = -Wl,-pie
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ALL_ASFLAGS = -f macho64 --prefix _
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else
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ALL_LDFLAGS = -pie -Wl,--fatal-warnings
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ALL_ASFLAGS = -f elf64
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endif
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ALL_CFLAGS += -std=c99 -fPIE -m64 $(CFLAGS)
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ALL_LDFLAGS += $(LDFLAGS)
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ALL_ASFLAGS += $(ASFLAGS)
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C_OBJS = $(patsubst %.c,%.o,$(wildcard *.c))
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AS_OBJS = $(patsubst %.asm,%.o,$(wildcard *.asm))
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ALL_OBJS = $(filter-out example.o,$(C_OBJS) $(AS_OBJS) vendor/unity.o)
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CC_CMD = $(CC) $(ALL_CFLAGS) -c -o $@ $<
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all: tests
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@./$<
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tests: $(ALL_OBJS)
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@$(CC) $(ALL_CFLAGS) $(ALL_LDFLAGS) -o $@ $(ALL_OBJS)
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%.o: %.asm
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@$(AS) $(ALL_ASFLAGS) -o $@ $<
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%.o: %.c
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@$(CC_CMD)
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vendor/unity.o: vendor/unity.c vendor/unity.h vendor/unity_internals.h
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@$(CC_CMD)
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clean:
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@rm -f *.o vendor/*.o tests
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.PHONY: all clean

‎exercises/practice/sieve/sieve.asm

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section .text
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global primes
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primes:
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; Provide your implementation here
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ret
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%ifidn __OUTPUT_FORMAT__,elf64
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section .note.GNU-stack noalloc noexec nowrite progbits
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%endif

‎exercises/practice/sieve/sieve_test.c

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// Version: 0
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#include "vendor/unity.h"
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#define BUFFER_SIZE 200
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#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
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extern uint32_t primes(uint32_t *buffer, uint32_t limit);
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void setUp(void) {
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}
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void tearDown(void) {
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}
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void test_no_primes_under_two(void) {
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uint32_t buffer[BUFFER_SIZE];
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TEST_ASSERT_EQUAL_UINT32(0, primes(buffer, 1));
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}
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void test_find_first_prime(void) {
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TEST_IGNORE();
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uint32_t buffer[BUFFER_SIZE];
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uint32_t expected[] = {2};
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TEST_ASSERT_EQUAL_UINT32(ARRAY_SIZE(expected), primes(buffer, 2));
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TEST_ASSERT_EQUAL_UINT32_ARRAY(expected, buffer, ARRAY_SIZE(expected));
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}
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void test_find_primes_up_to_10(void) {
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TEST_IGNORE();
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uint32_t buffer[BUFFER_SIZE];
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uint32_t expected[] = {2, 3, 5, 7};
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TEST_ASSERT_EQUAL_UINT32(ARRAY_SIZE(expected), primes(buffer, 10));
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TEST_ASSERT_EQUAL_UINT32_ARRAY(expected, buffer, ARRAY_SIZE(expected));
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}
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void test_limit_is_prime(void) {
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TEST_IGNORE();
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uint32_t buffer[BUFFER_SIZE];
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uint32_t expected[] = {2, 3, 5, 7, 11, 13};
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TEST_ASSERT_EQUAL_UINT32(ARRAY_SIZE(expected), primes(buffer, 13));
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TEST_ASSERT_EQUAL_UINT32_ARRAY(expected, buffer, ARRAY_SIZE(expected));
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}
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void test_find_primes_up_to_1000(void) {
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TEST_IGNORE();
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uint32_t buffer[BUFFER_SIZE];
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uint32_t expected[] = {
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2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67,
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71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149,
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151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229,
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233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293, 307, 311, 313,
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317, 331, 337, 347, 349, 353, 359, 367, 373, 379, 383, 389, 397, 401, 409,
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419, 421, 431, 433, 439, 443, 449, 457, 461, 463, 467, 479, 487, 491, 499,
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503, 509, 521, 523, 541, 547, 557, 563, 569, 571, 577, 587, 593, 599, 601,
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607, 613, 617, 619, 631, 641, 643, 647, 653, 659, 661, 673, 677, 683, 691,
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701, 709, 719, 727, 733, 739, 743, 751, 757, 761, 769, 773, 787, 797, 809,
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811, 821, 823, 827, 829, 839, 853, 857, 859, 863, 877, 881, 883, 887, 907,
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911, 919, 929, 937, 941, 947, 953, 967, 971, 977, 983, 991, 997
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};
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TEST_ASSERT_EQUAL_UINT32(ARRAY_SIZE(expected), primes(buffer, 1000));
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TEST_ASSERT_EQUAL_UINT32_ARRAY(expected, buffer, ARRAY_SIZE(expected));
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}
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int main(void) {
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UNITY_BEGIN();
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RUN_TEST(test_no_primes_under_two);
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RUN_TEST(test_find_first_prime);
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RUN_TEST(test_find_primes_up_to_10);
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RUN_TEST(test_limit_is_prime);
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RUN_TEST(test_find_primes_up_to_1000);
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return UNITY_END();
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}

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