89b1fdc443
We now detect if the return type will be set by passing the first argument as a pointer to stack memory from the callee's frame. This way, we do not have to worry about stack memory being overwritten. Besides this, we implement memset by either using wasm's memory.fill instruction when available, or lower it manually. In the future we can lower this to a compiler_rt call.
461 lines
11 KiB
Zig
461 lines
11 KiB
Zig
///! Contains all constants and types representing the wasm
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///! binary format, as specified by:
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///! https://webassembly.github.io/spec/core/
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const std = @import("std.zig");
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const testing = std.testing;
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// TODO: Add support for multi-byte ops (e.g. table operations)
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/// Wasm instruction opcodes
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///
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/// All instructions are defined as per spec:
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/// https://webassembly.github.io/spec/core/appendix/index-instructions.html
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pub const Opcode = enum(u8) {
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@"unreachable" = 0x00,
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nop = 0x01,
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block = 0x02,
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loop = 0x03,
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@"if" = 0x04,
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@"else" = 0x05,
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end = 0x0B,
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br = 0x0C,
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br_if = 0x0D,
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br_table = 0x0E,
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@"return" = 0x0F,
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call = 0x10,
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call_indirect = 0x11,
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drop = 0x1A,
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select = 0x1B,
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local_get = 0x20,
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local_set = 0x21,
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local_tee = 0x22,
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global_get = 0x23,
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global_set = 0x24,
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i32_load = 0x28,
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i64_load = 0x29,
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f32_load = 0x2A,
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f64_load = 0x2B,
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i32_load8_s = 0x2C,
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i32_load8_u = 0x2D,
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i32_load16_s = 0x2E,
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i32_load16_u = 0x2F,
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i64_load8_s = 0x30,
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i64_load8_u = 0x31,
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i64_load16_s = 0x32,
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i64_load16_u = 0x33,
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i64_load32_s = 0x34,
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i64_load32_u = 0x35,
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i32_store = 0x36,
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i64_store = 0x37,
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f32_store = 0x38,
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f64_store = 0x39,
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i32_store8 = 0x3A,
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i32_store16 = 0x3B,
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i64_store8 = 0x3C,
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i64_store16 = 0x3D,
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i64_store32 = 0x3E,
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memory_size = 0x3F,
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memory_grow = 0x40,
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i32_const = 0x41,
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i64_const = 0x42,
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f32_const = 0x43,
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f64_const = 0x44,
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i32_eqz = 0x45,
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i32_eq = 0x46,
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i32_ne = 0x47,
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i32_lt_s = 0x48,
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i32_lt_u = 0x49,
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i32_gt_s = 0x4A,
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i32_gt_u = 0x4B,
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i32_le_s = 0x4C,
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i32_le_u = 0x4D,
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i32_ge_s = 0x4E,
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i32_ge_u = 0x4F,
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i64_eqz = 0x50,
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i64_eq = 0x51,
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i64_ne = 0x52,
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i64_lt_s = 0x53,
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i64_lt_u = 0x54,
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i64_gt_s = 0x55,
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i64_gt_u = 0x56,
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i64_le_s = 0x57,
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i64_le_u = 0x58,
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i64_ge_s = 0x59,
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i64_ge_u = 0x5A,
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f32_eq = 0x5B,
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f32_ne = 0x5C,
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f32_lt = 0x5D,
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f32_gt = 0x5E,
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f32_le = 0x5F,
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f32_ge = 0x60,
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f64_eq = 0x61,
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f64_ne = 0x62,
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f64_lt = 0x63,
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f64_gt = 0x64,
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f64_le = 0x65,
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f64_ge = 0x66,
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i32_clz = 0x67,
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i32_ctz = 0x68,
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i32_popcnt = 0x69,
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i32_add = 0x6A,
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i32_sub = 0x6B,
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i32_mul = 0x6C,
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i32_div_s = 0x6D,
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i32_div_u = 0x6E,
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i32_rem_s = 0x6F,
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i32_rem_u = 0x70,
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i32_and = 0x71,
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i32_or = 0x72,
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i32_xor = 0x73,
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i32_shl = 0x74,
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i32_shr_s = 0x75,
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i32_shr_u = 0x76,
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i32_rotl = 0x77,
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i32_rotr = 0x78,
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i64_clz = 0x79,
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i64_ctz = 0x7A,
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i64_popcnt = 0x7B,
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i64_add = 0x7C,
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i64_sub = 0x7D,
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i64_mul = 0x7E,
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i64_div_s = 0x7F,
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i64_div_u = 0x80,
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i64_rem_s = 0x81,
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i64_rem_u = 0x82,
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i64_and = 0x83,
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i64_or = 0x84,
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i64_xor = 0x85,
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i64_shl = 0x86,
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i64_shr_s = 0x87,
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i64_shr_u = 0x88,
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i64_rotl = 0x89,
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i64_rotr = 0x8A,
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f32_abs = 0x8B,
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f32_neg = 0x8C,
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f32_ceil = 0x8D,
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f32_floor = 0x8E,
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f32_trunc = 0x8F,
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f32_nearest = 0x90,
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f32_sqrt = 0x91,
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f32_add = 0x92,
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f32_sub = 0x93,
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f32_mul = 0x94,
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f32_div = 0x95,
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f32_min = 0x96,
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f32_max = 0x97,
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f32_copysign = 0x98,
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f64_abs = 0x99,
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f64_neg = 0x9A,
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f64_ceil = 0x9B,
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f64_floor = 0x9C,
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f64_trunc = 0x9D,
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f64_nearest = 0x9E,
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f64_sqrt = 0x9F,
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f64_add = 0xA0,
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f64_sub = 0xA1,
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f64_mul = 0xA2,
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f64_div = 0xA3,
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f64_min = 0xA4,
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f64_max = 0xA5,
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f64_copysign = 0xA6,
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i32_wrap_i64 = 0xA7,
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i32_trunc_f32_s = 0xA8,
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i32_trunc_f32_u = 0xA9,
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i32_trunc_f64_s = 0xAA,
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i32_trunc_f64_u = 0xAB,
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i64_extend_i32_s = 0xAC,
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i64_extend_i32_u = 0xAD,
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i64_trunc_f32_s = 0xAE,
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i64_trunc_f32_u = 0xAF,
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i64_trunc_f64_s = 0xB0,
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i64_trunc_f64_u = 0xB1,
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f32_convert_i32_s = 0xB2,
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f32_convert_i32_u = 0xB3,
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f32_convert_i64_s = 0xB4,
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f32_convert_i64_u = 0xB5,
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f32_demote_f64 = 0xB6,
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f64_convert_i32_s = 0xB7,
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f64_convert_i32_u = 0xB8,
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f64_convert_i64_s = 0xB9,
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f64_convert_i64_u = 0xBA,
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f64_promote_f32 = 0xBB,
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i32_reinterpret_f32 = 0xBC,
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i64_reinterpret_f64 = 0xBD,
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f32_reinterpret_i32 = 0xBE,
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f64_reinterpret_i64 = 0xBF,
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i32_extend8_s = 0xC0,
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i32_extend16_s = 0xC1,
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i64_extend8_s = 0xC2,
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i64_extend16_s = 0xC3,
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i64_extend32_s = 0xC4,
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_,
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};
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/// Returns the integer value of an `Opcode`. Used by the Zig compiler
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/// to write instructions to the wasm binary file
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pub fn opcode(op: Opcode) u8 {
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return @enumToInt(op);
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}
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test "Wasm - opcodes" {
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// Ensure our opcodes values remain intact as certain values are skipped due to them being reserved
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const i32_const = opcode(.i32_const);
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const end = opcode(.end);
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const drop = opcode(.drop);
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const local_get = opcode(.local_get);
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const i64_extend32_s = opcode(.i64_extend32_s);
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try testing.expectEqual(@as(u16, 0x41), i32_const);
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try testing.expectEqual(@as(u16, 0x0B), end);
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try testing.expectEqual(@as(u16, 0x1A), drop);
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try testing.expectEqual(@as(u16, 0x20), local_get);
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try testing.expectEqual(@as(u16, 0xC4), i64_extend32_s);
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}
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/// Opcodes that require a prefix `0xFC`
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pub const PrefixedOpcode = enum(u8) {
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i32_trunc_sat_f32_s = 0x00,
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i32_trunc_sat_f32_u = 0x01,
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i32_trunc_sat_f64_s = 0x02,
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i32_trunc_sat_f64_u = 0x03,
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i64_trunc_sat_f32_s = 0x04,
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i64_trunc_sat_f32_u = 0x05,
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i64_trunc_sat_f64_s = 0x06,
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i64_trunc_sat_f64_u = 0x07,
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memory_init = 0x08,
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data_drop = 0x09,
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memory_copy = 0x0A,
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memory_fill = 0x0B,
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table_init = 0x0C,
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elem_drop = 0x0D,
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table_copy = 0x0E,
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table_grow = 0x0F,
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table_size = 0x10,
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table_fill = 0x11,
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};
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/// Enum representing all Wasm value types as per spec:
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/// https://webassembly.github.io/spec/core/binary/types.html
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pub const Valtype = enum(u8) {
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i32 = 0x7F,
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i64 = 0x7E,
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f32 = 0x7D,
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f64 = 0x7C,
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};
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/// Returns the integer value of a `Valtype`
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pub fn valtype(value: Valtype) u8 {
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return @enumToInt(value);
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}
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/// Reference types, where the funcref references to a function regardless of its type
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/// and ref references an object from the embedder.
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pub const RefType = enum(u8) {
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funcref = 0x70,
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externref = 0x6F,
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};
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/// Returns the integer value of a `Reftype`
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pub fn reftype(value: RefType) u8 {
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return @enumToInt(value);
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}
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test "Wasm - valtypes" {
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const _i32 = valtype(.i32);
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const _i64 = valtype(.i64);
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const _f32 = valtype(.f32);
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const _f64 = valtype(.f64);
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try testing.expectEqual(@as(u8, 0x7F), _i32);
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try testing.expectEqual(@as(u8, 0x7E), _i64);
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try testing.expectEqual(@as(u8, 0x7D), _f32);
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try testing.expectEqual(@as(u8, 0x7C), _f64);
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}
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/// Limits classify the size range of resizeable storage associated with memory types and table types.
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pub const Limits = struct {
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min: u32,
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max: ?u32,
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};
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/// Initialization expressions are used to set the initial value on an object
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/// when a wasm module is being loaded.
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pub const InitExpression = union(enum) {
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i32_const: i32,
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i64_const: i64,
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f32_const: f32,
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f64_const: f64,
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global_get: u32,
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};
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/// Represents a function entry, holding the index to its type
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pub const Func = struct {
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type_index: u32,
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};
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/// Tables are used to hold pointers to opaque objects.
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/// This can either by any function, or an object from the host.
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pub const Table = struct {
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limits: Limits,
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reftype: RefType,
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};
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/// Describes the layout of the memory where `min` represents
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/// the minimal amount of pages, and the optional `max` represents
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/// the max pages. When `null` will allow the host to determine the
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/// amount of pages.
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pub const Memory = struct {
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limits: Limits,
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};
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/// Represents the type of a `Global` or an imported global.
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pub const GlobalType = struct {
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valtype: Valtype,
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mutable: bool,
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};
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pub const Global = struct {
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global_type: GlobalType,
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init: InitExpression,
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};
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/// Notates an object to be exported from wasm
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/// to the host.
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pub const Export = struct {
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name: []const u8,
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kind: ExternalKind,
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index: u32,
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};
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/// Element describes the layout of the table that can
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/// be found at `table_index`
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pub const Element = struct {
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table_index: u32,
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offset: InitExpression,
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func_indexes: []const u32,
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};
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/// Imports are used to import objects from the host
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pub const Import = struct {
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module_name: []const u8,
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name: []const u8,
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kind: Kind,
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pub const Kind = union(ExternalKind) {
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function: u32,
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table: Table,
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memory: Limits,
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global: GlobalType,
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};
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};
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/// `Type` represents a function signature type containing both
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/// a slice of parameters as well as a slice of return values.
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pub const Type = struct {
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params: []const Valtype,
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returns: []const Valtype,
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pub fn format(self: Type, comptime fmt: []const u8, opt: std.fmt.FormatOptions, writer: anytype) !void {
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_ = fmt;
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_ = opt;
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try writer.writeByte('(');
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for (self.params) |param, i| {
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try writer.print("{s}", .{@tagName(param)});
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if (i + 1 != self.params.len) {
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try writer.writeAll(", ");
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}
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}
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try writer.writeAll(") -> ");
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if (self.returns.len == 0) {
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try writer.writeAll("nil");
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} else {
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for (self.returns) |return_ty, i| {
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try writer.print("{s}", .{@tagName(return_ty)});
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if (i + 1 != self.returns.len) {
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try writer.writeAll(", ");
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}
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}
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}
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}
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pub fn eql(self: Type, other: Type) bool {
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return std.mem.eql(Valtype, self.params, other.params) and
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std.mem.eql(Valtype, self.returns, other.returns);
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}
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pub fn deinit(self: *Type, gpa: std.mem.Allocator) void {
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gpa.free(self.params);
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gpa.free(self.returns);
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self.* = undefined;
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}
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};
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/// Wasm module sections as per spec:
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/// https://webassembly.github.io/spec/core/binary/modules.html
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pub const Section = enum(u8) {
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custom,
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type,
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import,
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function,
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table,
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memory,
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global,
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@"export",
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start,
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element,
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code,
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data,
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data_count,
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_,
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};
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/// Returns the integer value of a given `Section`
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pub fn section(val: Section) u8 {
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return @enumToInt(val);
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}
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/// The kind of the type when importing or exporting to/from the host environment
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/// https://webassembly.github.io/spec/core/syntax/modules.html
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pub const ExternalKind = enum(u8) {
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function,
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table,
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memory,
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global,
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};
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/// Returns the integer value of a given `ExternalKind`
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pub fn externalKind(val: ExternalKind) u8 {
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return @enumToInt(val);
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}
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/// Defines the enum values for each subsection id for the "Names" custom section
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/// as described by:
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/// https://webassembly.github.io/spec/core/appendix/custom.html?highlight=name#name-section
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pub const NameSubsection = enum(u8) {
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module,
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function,
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local,
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label,
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type,
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table,
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memory,
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global,
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elem_segment,
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data_segment,
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};
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// type constants
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pub const element_type: u8 = 0x70;
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pub const function_type: u8 = 0x60;
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pub const result_type: u8 = 0x40;
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/// Represents a block which will not return a value
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pub const block_empty: u8 = 0x40;
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// binary constants
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pub const magic = [_]u8{ 0x00, 0x61, 0x73, 0x6D }; // \0asm
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pub const version = [_]u8{ 0x01, 0x00, 0x00, 0x00 }; // version 1 (MVP)
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// Each wasm page size is 64kB
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pub const page_size = 64 * 1024;
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