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const std = @import("std");
const gc = @import("../gc.zig");
const value = @import("../value.zig");
const Hval = gc.Hval;
const Value = value.Value;
// Zig API
pub fn check(v: Value) bool {
return v.isPtr();
}
pub fn assert(v: Value) void {
if (!check(v)) {
v.dump();
@panic("not a pointer");
}
}
// Foreign Pointers
pub fn checkForeign(v: Value) bool {
return check(v) and v.ptr.is_foreign;
}
pub fn assertForeign(v: Value) void {
if (!checkForeign(v)) {
v.dump();
@panic("not foreign pointer");
}
}
pub fn packForeign(int: u50) Value {
return .{ .fptr = .{ .value = int } };
}
pub fn unpackForeign(v: Value) u50 {
assertForeign(v);
return v.fptr.value;
}
// Zisp Pointers
pub fn checkZisp(v: Value) bool {
return check(v) and !v.ptr.is_foreign;
}
pub fn assertZisp(v: Value) void {
if (!checkZisp(v)) {
v.dump();
@panic("not zisp pointer");
}
}
pub fn checkWeak(v: Value) bool {
return checkZisp(v) and v.zptr.is_weak;
}
pub fn assertWeak(v: Value) void {
if (!checkWeak(v)) {
v.dump();
@panic("not zisp weak pointer");
}
}
pub fn checkZispTag(v: Value, tag: Tag) bool {
return checkZisp(v) and unpack(v).@"1" == tag;
}
pub fn assertZispTag(v: Value, tag: Tag) void {
if (!checkZispTag(v, tag)) {
v.dump();
@panic("not zisp pointer or wrong tag");
}
}
pub fn checkStrong(v: Value) bool {
return checkZisp(v) and !v.zptr.is_weak;
}
pub fn assertStrong(v: Value) void {
if (!checkStrong(v)) {
v.dump();
@panic("not zisp strong pointer");
}
}
pub fn packZisp(ptr: *Hval, tag: Tag, is_weak: bool) Value {
return .{ .zptr = .{
.tagged_value = tagPtr(ptr, tag),
.is_weak = is_weak,
} };
}
pub fn pack(ptr: *Hval, tag: Tag) Value {
return packZisp(ptr, tag, false);
}
pub fn packWeak(ptr: *Hval, tag: Tag) Value {
return packZisp(ptr, tag, true);
}
// Unpacks weak as well; no need for a separate fn.
pub fn unpack(v: Value) struct { *Hval, Tag } {
assertZisp(v);
return untagPtr(v.zptr.tagged_value);
}
pub fn setWeakNull(v: *Value) void {
assertWeak(v.*);
v.zptr.tagged_value = 0;
}
pub fn isWeakNull(v: Value) bool {
assertWeak(v);
return v.zptr.tagged_value == 0;
}
fn tagPtr(ptr: *Hval, tag: Tag) u48 {
const int: usize = @intFromPtr(ptr);
const untagged: u48 = @intCast(int);
return untagged | @intFromEnum(tag);
}
fn untagPtr(tagged: u48) struct { *Hval, Tag } {
const untagged: u48 = tagged & 0xfffffffffff8;
const ptr: *Hval = @ptrFromInt(untagged);
const int: u3 = @truncate(tagged);
const tag: Tag = @enumFromInt(int);
return .{ ptr, tag };
}
pub const Tag = enum(u3) {
/// Pair aka cons cell aka *[2]Value
pair,
/// Sequence of various kinds (16-bit meta, 48-bit length, then data)
seq,
/// Procedure
proc,
};
// Zisp API
pub fn predForeign(v: Value) Value {
return value.boole.pack(checkForeign(v));
}
pub fn makeWeak(v: Value) Value {
assertStrong(v);
var copy = v;
copy.zptr.is_weak = true;
return copy;
}
pub fn predWeak(v: Value) Value {
return value.boole.pack(checkWeak(v));
}
pub fn predWeakNull(v: Value) Value {
return value.boole.pack(isWeakNull(v));
}
pub fn getWeak(v: Value) Value {
if (isWeakNull(v)) {
return value.boole.f;
} else {
var copy = v;
copy.zptr.is_weak = false;
return copy;
}
}
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