//! library/kernel/memory — the process's memory interface: the heap allocator, DMA-capable
//! buffers, shared-memory regions, and the raw `mmap` grant they all sit on. One flat module
//! (formerly runtime.heap / runtime.dma / runtime.shared_memory, plus the `mmap` wrappers that
//! lived in the system.zig dumping ground). Its private files are heap.zig, dma.zig, and
//! shared-memory.zig — imported only here, so the heap's state and C symbols exist once.

const abi = @import("abi");
const sc = @import("system-call");
const heap = @import("heap.zig");
const dma = @import("dma.zig");
const shared = @import("shared-memory.zig");

// --- the heap: a std.mem.Allocator over a first-fit free list (C malloc/free are also
//     exported from heap.zig, compiled once here) ---
pub const allocator = heap.allocator;

// --- the raw grant every allocation sits on ---
pub const PROT_READ: usize = abi.prot_read;
pub const PROT_WRITE: usize = abi.prot_write;
pub const PROT_EXEC: usize = abi.prot_exec;

/// Grant `len` bytes (rounded up to whole pages) of fresh, zeroed, writable memory and
/// return the base virtual address. On failure returns a value in the top page (`mmapFailed`).
pub fn mmap(len: usize, prot: usize) usize {
    return sc.systemCall2(.mmap, len, prot);
}
/// Release a range previously handed out by `mmap`.
pub fn munmap(base: usize, len: usize) usize {
    return sc.systemCall2(.munmap, base, len);
}
/// Whether an `mmap` return value is an error (a wrapped -errno lands in the top page).
pub inline fn mmapFailed(ret: usize) bool {
    return ret > ~@as(usize, 0) - 4095;
}

// --- DMA-capable buffers: physically contiguous, pinned, uncacheable, physical address known ---
pub const DmaRegion = dma.Region;
pub const dma_coherent = dma.coherent;
pub const dma_write_combining = dma.write_combining;
pub const dma_below_4g = dma.below_4g;
pub const dma_shareable = dma.shareable;
pub const dmaAlloc = dma.alloc;
pub const dmaFree = dma.free;

// --- shared-memory regions: a capability handed to another process over an ipc_call send_cap ---
pub const SharedRegion = shared.Region;
pub const sharedCreate = shared.create;
pub const sharedMap = shared.map;
pub const sharedPhysical = shared.physical;