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FIFO Queue (First-In-First-Out)

Pure Nim implementation of a fixed-capacity FIFO queue with zero heap allocation.

Features:

Fixed capacity at compile time (no dynamic allocation)
Thread-safe for single producer/single consumer
Audio-rate safe (no locks, predictable performance)
Generic type support via templates

Use Cases:

Event queues
Message passing between threads
Audio sample buffering
Command queues

Memory:

Stack allocated only
Size known at compile time
Zero runtime overhead

Usage:

import nimphea_fifo

# Create FIFO for 16 integers
var queue: Fifo[16, int]
queue.init()

# Push values
discard queue.push(42)
discard queue.push(100)

# Pop values (FIFO order)
var value: int
if queue.pop(value):
  echo value  # 42 (first in, first out)

# Check state
echo queue.len()      # Current count
echo queue.isEmpty()  # false
echo queue.isFull()   # false

Types

Fifo[N; T] = object

Fixed-capacity FIFO queue

Generic Parameters:

N - Capacity (must be known at compile time)
T - Element type

Fields:

data - Fixed array storage
head - Read position
tail - Write position
count - Current number of elements

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Procs

proc `$`[N: static int; T](this: Fifo[N, T]): string: Convert FIFO to string representation (for debugging)

Example:

echo queue # "Fifo[16, int](count=5/16)"
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proc capacity[N: static int; T](this: Fifo[N, T]): int {.inline.}: Get maximum capacity

Returns: Maximum capacity (compile-time constant N)

Example:

echo queue.capacity() # 32
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proc clear[N: static int; T](this: var Fifo[N, T]): Clear all elements from the queue

Example:

queue.clear()
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proc init[N: static int; T](this: var Fifo[N, T]): Initialize the FIFO queue

Example:

var queue: Fifo[32, float32] queue.init()
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proc isEmpty[N: static int; T](this: Fifo[N, T]): bool {.inline.}: Check if queue is empty

Returns: true if empty, false otherwise

Example:

if queue.isEmpty(): echo "Queue is empty"
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proc isFull[N: static int; T](this: Fifo[N, T]): bool {.inline.}: Check if queue is full

Returns: true if full, false otherwise

Example:

if queue.isFull(): echo "Queue is full, cannot push"
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proc len[N: static int; T](this: Fifo[N, T]): int {.inline.}: Get current number of elements

Returns: Number of elements (0 to N)

Example:

echo queue.len() # e.g., 5
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proc peek[N: static int; T](this: Fifo[N, T]; value: var T): bool {.inline.}: Peek at the next value without removing it

Parameters:

value - Output parameter to receive the peeked value

Returns: true if successful, false if queue was empty

Example:

var val: int if queue.peek(val): echo "Next value: ", val # Queue unchanged
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proc pop[N: static int; T](this: var Fifo[N, T]; value: var T): bool {.inline.}: Pop a value from the queue (from head)

Parameters:

value - Output parameter to receive the popped value

Returns: true if successful, false if queue was empty

Example:

var val: int if queue.pop(val): echo "Popped: ", val else: echo "Queue empty"
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proc push[N: static int; T](this: var Fifo[N, T]; value: T): bool {.inline.}: Push a value onto the queue (at tail)

Parameters:

value - Element to push

Returns: true if successful, false if queue was full

Example:

if not queue.push(42): echo "Queue full, push failed"
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nimphea/nimphea_fifo

FIFO Queue (First-In-First-Out)

Types

Procs