///! Contains all constants and types representing the wasm ///! binary format, as specified by: ///! https://webassembly.github.io/spec/core/ const std = @import("std.zig"); const testing = std.testing; // TODO: Add support for multi-byte ops (e.g. table operations) /// Wasm instruction opcodes /// /// All instructions are defined as per spec: /// https://webassembly.github.io/spec/core/appendix/index-instructions.html pub const Opcode = enum(u8) { @"unreachable" = 0x00, nop = 0x01, block = 0x02, loop = 0x03, @"if" = 0x04, @"else" = 0x05, end = 0x0B, br = 0x0C, br_if = 0x0D, br_table = 0x0E, @"return" = 0x0F, call = 0x10, call_indirect = 0x11, drop = 0x1A, select = 0x1B, local_get = 0x20, local_set = 0x21, local_tee = 0x22, global_get = 0x23, global_set = 0x24, i32_load = 0x28, i64_load = 0x29, f32_load = 0x2A, f64_load = 0x2B, i32_load8_s = 0x2C, i32_load8_u = 0x2D, i32_load16_s = 0x2E, i32_load16_u = 0x2F, i64_load8_s = 0x30, i64_load8_u = 0x31, i64_load16_s = 0x32, i64_load16_u = 0x33, i64_load32_s = 0x34, i64_load32_u = 0x35, i32_store = 0x36, i64_store = 0x37, f32_store = 0x38, f64_store = 0x39, i32_store8 = 0x3A, i32_store16 = 0x3B, i64_store8 = 0x3C, i64_store16 = 0x3D, i64_store32 = 0x3E, memory_size = 0x3F, memory_grow = 0x40, i32_const = 0x41, i64_const = 0x42, f32_const = 0x43, f64_const = 0x44, i32_eqz = 0x45, i32_eq = 0x46, i32_ne = 0x47, i32_lt_s = 0x48, i32_lt_u = 0x49, i32_gt_s = 0x4A, i32_gt_u = 0x4B, i32_le_s = 0x4C, i32_le_u = 0x4D, i32_ge_s = 0x4E, i32_ge_u = 0x4F, i64_eqz = 0x50, i64_eq = 0x51, i64_ne = 0x52, i64_lt_s = 0x53, i64_lt_u = 0x54, i64_gt_s = 0x55, i64_gt_u = 0x56, i64_le_s = 0x57, i64_le_u = 0x58, i64_ge_s = 0x59, i64_ge_u = 0x5A, f32_eq = 0x5B, f32_ne = 0x5C, f32_lt = 0x5D, f32_gt = 0x5E, f32_le = 0x5F, f32_ge = 0x60, f64_eq = 0x61, f64_ne = 0x62, f64_lt = 0x63, f64_gt = 0x64, f64_le = 0x65, f64_ge = 0x66, i32_clz = 0x67, i32_ctz = 0x68, i32_popcnt = 0x69, i32_add = 0x6A, i32_sub = 0x6B, i32_mul = 0x6C, i32_div_s = 0x6D, i32_div_u = 0x6E, i32_rem_s = 0x6F, i32_rem_u = 0x70, i32_and = 0x71, i32_or = 0x72, i32_xor = 0x73, i32_shl = 0x74, i32_shr_s = 0x75, i32_shr_u = 0x76, i32_rotl = 0x77, i32_rotr = 0x78, i64_clz = 0x79, i64_ctz = 0x7A, i64_popcnt = 0x7B, i64_add = 0x7C, i64_sub = 0x7D, i64_mul = 0x7E, i64_div_s = 0x7F, i64_div_u = 0x80, i64_rem_s = 0x81, i64_rem_u = 0x82, i64_and = 0x83, i64_or = 0x84, i64_xor = 0x85, i64_shl = 0x86, i64_shr_s = 0x87, i64_shr_u = 0x88, i64_rotl = 0x89, i64_rotr = 0x8A, f32_abs = 0x8B, f32_neg = 0x8C, f32_ceil = 0x8D, f32_floor = 0x8E, f32_trunc = 0x8F, f32_nearest = 0x90, f32_sqrt = 0x91, f32_add = 0x92, f32_sub = 0x93, f32_mul = 0x94, f32_div = 0x95, f32_min = 0x96, f32_max = 0x97, f32_copysign = 0x98, f64_abs = 0x99, f64_neg = 0x9A, f64_ceil = 0x9B, f64_floor = 0x9C, f64_trunc = 0x9D, f64_nearest = 0x9E, f64_sqrt = 0x9F, f64_add = 0xA0, f64_sub = 0xA1, f64_mul = 0xA2, f64_div = 0xA3, f64_min = 0xA4, f64_max = 0xA5, f64_copysign = 0xA6, i32_wrap_i64 = 0xA7, i32_trunc_f32_s = 0xA8, i32_trunc_f32_u = 0xA9, i32_trunc_f64_s = 0xAA, i32_trunc_f64_u = 0xAB, i64_extend_i32_s = 0xAC, i64_extend_i32_u = 0xAD, i64_trunc_f32_s = 0xAE, i64_trunc_f32_u = 0xAF, i64_trunc_f64_s = 0xB0, i64_trunc_f64_u = 0xB1, f32_convert_i32_s = 0xB2, f32_convert_i32_u = 0xB3, f32_convert_i64_s = 0xB4, f32_convert_i64_u = 0xB5, f32_demote_f64 = 0xB6, f64_convert_i32_s = 0xB7, f64_convert_i32_u = 0xB8, f64_convert_i64_s = 0xB9, f64_convert_i64_u = 0xBA, f64_promote_f32 = 0xBB, i32_reinterpret_f32 = 0xBC, i64_reinterpret_f64 = 0xBD, f32_reinterpret_i32 = 0xBE, f64_reinterpret_i64 = 0xBF, i32_extend8_s = 0xC0, i32_extend16_s = 0xC1, i64_extend8_s = 0xC2, i64_extend16_s = 0xC3, i64_extend32_s = 0xC4, _, }; /// Returns the integer value of an `Opcode`. Used by the Zig compiler /// to write instructions to the wasm binary file pub fn opcode(op: Opcode) u8 { return @enumToInt(op); } test "Wasm - opcodes" { // Ensure our opcodes values remain intact as certain values are skipped due to them being reserved const i32_const = opcode(.i32_const); const end = opcode(.end); const drop = opcode(.drop); const local_get = opcode(.local_get); const i64_extend32_s = opcode(.i64_extend32_s); try testing.expectEqual(@as(u16, 0x41), i32_const); try testing.expectEqual(@as(u16, 0x0B), end); try testing.expectEqual(@as(u16, 0x1A), drop); try testing.expectEqual(@as(u16, 0x20), local_get); try testing.expectEqual(@as(u16, 0xC4), i64_extend32_s); } /// Opcodes that require a prefix `0xFC` pub const PrefixedOpcode = enum(u8) { i32_trunc_sat_f32_s = 0x00, i32_trunc_sat_f32_u = 0x01, i32_trunc_sat_f64_s = 0x02, i32_trunc_sat_f64_u = 0x03, i64_trunc_sat_f32_s = 0x04, i64_trunc_sat_f32_u = 0x05, i64_trunc_sat_f64_s = 0x06, i64_trunc_sat_f64_u = 0x07, memory_init = 0x08, data_drop = 0x09, memory_copy = 0x0A, memory_fill = 0x0B, table_init = 0x0C, elem_drop = 0x0D, table_copy = 0x0E, table_grow = 0x0F, table_size = 0x10, table_fill = 0x11, }; /// Enum representing all Wasm value types as per spec: /// https://webassembly.github.io/spec/core/binary/types.html pub const Valtype = enum(u8) { i32 = 0x7F, i64 = 0x7E, f32 = 0x7D, f64 = 0x7C, }; /// Returns the integer value of a `Valtype` pub fn valtype(value: Valtype) u8 { return @enumToInt(value); } /// Reference types, where the funcref references to a function regardless of its type /// and ref references an object from the embedder. pub const RefType = enum(u8) { funcref = 0x70, externref = 0x6F, }; /// Returns the integer value of a `Reftype` pub fn reftype(value: RefType) u8 { return @enumToInt(value); } test "Wasm - valtypes" { const _i32 = valtype(.i32); const _i64 = valtype(.i64); const _f32 = valtype(.f32); const _f64 = valtype(.f64); try testing.expectEqual(@as(u8, 0x7F), _i32); try testing.expectEqual(@as(u8, 0x7E), _i64); try testing.expectEqual(@as(u8, 0x7D), _f32); try testing.expectEqual(@as(u8, 0x7C), _f64); } /// Limits classify the size range of resizeable storage associated with memory types and table types. pub const Limits = struct { min: u32, max: ?u32, }; /// Initialization expressions are used to set the initial value on an object /// when a wasm module is being loaded. pub const InitExpression = union(enum) { i32_const: i32, i64_const: i64, f32_const: f32, f64_const: f64, global_get: u32, }; /// Represents a function entry, holding the index to its type pub const Func = struct { type_index: u32, }; /// Tables are used to hold pointers to opaque objects. /// This can either by any function, or an object from the host. pub const Table = struct { limits: Limits, reftype: RefType, }; /// Describes the layout of the memory where `min` represents /// the minimal amount of pages, and the optional `max` represents /// the max pages. When `null` will allow the host to determine the /// amount of pages. pub const Memory = struct { limits: Limits, }; /// Represents the type of a `Global` or an imported global. pub const GlobalType = struct { valtype: Valtype, mutable: bool, }; pub const Global = struct { global_type: GlobalType, init: InitExpression, }; /// Notates an object to be exported from wasm /// to the host. pub const Export = struct { name: []const u8, kind: ExternalKind, index: u32, }; /// Element describes the layout of the table that can /// be found at `table_index` pub const Element = struct { table_index: u32, offset: InitExpression, func_indexes: []const u32, }; /// Imports are used to import objects from the host pub const Import = struct { module_name: []const u8, name: []const u8, kind: Kind, pub const Kind = union(ExternalKind) { function: u32, table: Table, memory: Limits, global: GlobalType, }; }; /// `Type` represents a function signature type containing both /// a slice of parameters as well as a slice of return values. pub const Type = struct { params: []const Valtype, returns: []const Valtype, pub fn format(self: Type, comptime fmt: []const u8, opt: std.fmt.FormatOptions, writer: anytype) !void { _ = fmt; _ = opt; try writer.writeByte('('); for (self.params) |param, i| { try writer.print("{s}", .{@tagName(param)}); if (i + 1 != self.params.len) { try writer.writeAll(", "); } } try writer.writeAll(") -> "); if (self.returns.len == 0) { try writer.writeAll("nil"); } else { for (self.returns) |return_ty, i| { try writer.print("{s}", .{@tagName(return_ty)}); if (i + 1 != self.returns.len) { try writer.writeAll(", "); } } } } pub fn eql(self: Type, other: Type) bool { return std.mem.eql(Valtype, self.params, other.params) and std.mem.eql(Valtype, self.returns, other.returns); } pub fn deinit(self: *Type, gpa: std.mem.Allocator) void { gpa.free(self.params); gpa.free(self.returns); self.* = undefined; } }; /// Wasm module sections as per spec: /// https://webassembly.github.io/spec/core/binary/modules.html pub const Section = enum(u8) { custom, type, import, function, table, memory, global, @"export", start, element, code, data, data_count, _, }; /// Returns the integer value of a given `Section` pub fn section(val: Section) u8 { return @enumToInt(val); } /// The kind of the type when importing or exporting to/from the host environment /// https://webassembly.github.io/spec/core/syntax/modules.html pub const ExternalKind = enum(u8) { function, table, memory, global, }; /// Returns the integer value of a given `ExternalKind` pub fn externalKind(val: ExternalKind) u8 { return @enumToInt(val); } /// Defines the enum values for each subsection id for the "Names" custom section /// as described by: /// https://webassembly.github.io/spec/core/appendix/custom.html?highlight=name#name-section pub const NameSubsection = enum(u8) { module, function, local, label, type, table, memory, global, elem_segment, data_segment, }; // type constants pub const element_type: u8 = 0x70; pub const function_type: u8 = 0x60; pub const result_type: u8 = 0x40; /// Represents a block which will not return a value pub const block_empty: u8 = 0x40; // binary constants pub const magic = [_]u8{ 0x00, 0x61, 0x73, 0x6D }; // \0asm pub const version = [_]u8{ 0x01, 0x00, 0x00, 0x00 }; // version 1 (MVP) // Each wasm page size is 64kB pub const page_size = 64 * 1024;