257 lines
9.7 KiB
Zig
257 lines
9.7 KiB
Zig
const std = @import("std");
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const testing = std.testing;
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pub fn readULEB128(comptime T: type, in_stream: var) !T {
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const ShiftT = std.meta.IntType(false, std.math.log2(T.bit_count));
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var result: T = 0;
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var shift: usize = 0;
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while (true) {
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const byte = try in_stream.readByte();
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if (shift > T.bit_count)
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return error.Overflow;
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var operand: T = undefined;
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if (@shlWithOverflow(T, byte & 0x7f, @intCast(ShiftT, shift), &operand))
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return error.Overflow;
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result |= operand;
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if ((byte & 0x80) == 0)
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return result;
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shift += 7;
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}
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}
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pub fn readULEB128Mem(comptime T: type, ptr: *[*]const u8) !T {
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const ShiftT = std.meta.IntType(false, std.math.log2(T.bit_count));
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var result: T = 0;
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var shift: usize = 0;
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var i: usize = 0;
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while (true) : (i += 1) {
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const byte = ptr.*[i];
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if (shift > T.bit_count)
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return error.Overflow;
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var operand: T = undefined;
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if (@shlWithOverflow(T, byte & 0x7f, @intCast(ShiftT, shift), &operand))
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return error.Overflow;
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result |= operand;
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if ((byte & 0x80) == 0) {
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ptr.* += i + 1;
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return result;
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}
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shift += 7;
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}
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}
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pub fn readILEB128(comptime T: type, in_stream: var) !T {
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const UT = std.meta.IntType(false, T.bit_count);
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const ShiftT = std.meta.IntType(false, std.math.log2(T.bit_count));
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var result: UT = 0;
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var shift: usize = 0;
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while (true) {
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const byte: u8 = try in_stream.readByte();
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if (shift > T.bit_count)
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return error.Overflow;
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var operand: UT = undefined;
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if (@shlWithOverflow(UT, @as(UT, byte & 0x7f), @intCast(ShiftT, shift), &operand)) {
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if (byte != 0x7f)
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return error.Overflow;
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}
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result |= operand;
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shift += 7;
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if ((byte & 0x80) == 0) {
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if (shift < T.bit_count and (byte & 0x40) != 0) {
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result |= @bitCast(UT, @intCast(T, -1)) << @intCast(ShiftT, shift);
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}
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return @bitCast(T, result);
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}
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}
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}
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pub fn readILEB128Mem(comptime T: type, ptr: *[*]const u8) !T {
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const UT = std.meta.IntType(false, T.bit_count);
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const ShiftT = std.meta.IntType(false, std.math.log2(T.bit_count));
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var result: UT = 0;
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var shift: usize = 0;
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var i: usize = 0;
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while (true) : (i += 1) {
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const byte = ptr.*[i];
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if (shift > T.bit_count)
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return error.Overflow;
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var operand: UT = undefined;
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if (@shlWithOverflow(UT, @as(UT, byte & 0x7f), @intCast(ShiftT, shift), &operand)) {
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if (byte != 0x7f)
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return error.Overflow;
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}
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result |= operand;
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shift += 7;
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if ((byte & 0x80) == 0) {
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if (shift < T.bit_count and (byte & 0x40) != 0) {
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result |= @bitCast(UT, @intCast(T, -1)) << @intCast(ShiftT, shift);
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}
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ptr.* += i + 1;
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return @bitCast(T, result);
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}
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}
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}
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fn test_read_stream_ileb128(comptime T: type, encoded: []const u8) !T {
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var in_stream = std.io.fixedBufferStream(encoded);
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return try readILEB128(T, in_stream.inStream());
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}
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fn test_read_stream_uleb128(comptime T: type, encoded: []const u8) !T {
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var in_stream = std.io.fixedBufferStream(encoded);
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return try readULEB128(T, in_stream.inStream());
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}
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fn test_read_ileb128(comptime T: type, encoded: []const u8) !T {
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var in_stream = std.io.fixedBufferStream(encoded);
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const v1 = readILEB128(T, in_stream.inStream());
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var in_ptr = encoded.ptr;
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const v2 = readILEB128Mem(T, &in_ptr);
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testing.expectEqual(v1, v2);
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return v1;
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}
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fn test_read_uleb128(comptime T: type, encoded: []const u8) !T {
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var in_stream = std.io.fixedBufferStream(encoded);
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const v1 = readULEB128(T, in_stream.inStream());
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var in_ptr = encoded.ptr;
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const v2 = readULEB128Mem(T, &in_ptr);
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testing.expectEqual(v1, v2);
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return v1;
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}
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fn test_read_ileb128_seq(comptime T: type, comptime N: usize, encoded: []const u8) void {
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var in_stream = std.io.fixedBufferStream(encoded);
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var in_ptr = encoded.ptr;
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var i: usize = 0;
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while (i < N) : (i += 1) {
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const v1 = readILEB128(T, in_stream.inStream());
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const v2 = readILEB128Mem(T, &in_ptr);
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testing.expectEqual(v1, v2);
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}
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}
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fn test_read_uleb128_seq(comptime T: type, comptime N: usize, encoded: []const u8) void {
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var in_stream = std.io.fixedBufferStream(encoded);
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var in_ptr = encoded.ptr;
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var i: usize = 0;
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while (i < N) : (i += 1) {
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const v1 = readULEB128(T, in_stream.inStream());
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const v2 = readULEB128Mem(T, &in_ptr);
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testing.expectEqual(v1, v2);
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}
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}
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test "deserialize signed LEB128" {
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// Truncated
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testing.expectError(error.EndOfStream, test_read_stream_ileb128(i64, "\x80"));
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// Overflow
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testing.expectError(error.Overflow, test_read_ileb128(i8, "\x80\x80\x40"));
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testing.expectError(error.Overflow, test_read_ileb128(i16, "\x80\x80\x80\x40"));
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testing.expectError(error.Overflow, test_read_ileb128(i32, "\x80\x80\x80\x80\x40"));
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testing.expectError(error.Overflow, test_read_ileb128(i64, "\x80\x80\x80\x80\x80\x80\x80\x80\x80\x40"));
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testing.expectError(error.Overflow, test_read_ileb128(i8, "\xff\x7e"));
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// Decode SLEB128
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testing.expect((try test_read_ileb128(i64, "\x00")) == 0);
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testing.expect((try test_read_ileb128(i64, "\x01")) == 1);
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testing.expect((try test_read_ileb128(i64, "\x3f")) == 63);
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testing.expect((try test_read_ileb128(i64, "\x40")) == -64);
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testing.expect((try test_read_ileb128(i64, "\x41")) == -63);
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testing.expect((try test_read_ileb128(i64, "\x7f")) == -1);
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testing.expect((try test_read_ileb128(i64, "\x80\x01")) == 128);
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testing.expect((try test_read_ileb128(i64, "\x81\x01")) == 129);
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testing.expect((try test_read_ileb128(i64, "\xff\x7e")) == -129);
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testing.expect((try test_read_ileb128(i64, "\x80\x7f")) == -128);
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testing.expect((try test_read_ileb128(i64, "\x81\x7f")) == -127);
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testing.expect((try test_read_ileb128(i64, "\xc0\x00")) == 64);
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testing.expect((try test_read_ileb128(i64, "\xc7\x9f\x7f")) == -12345);
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testing.expect((try test_read_ileb128(i8, "\xff\x7f")) == -1);
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testing.expect((try test_read_ileb128(i16, "\xff\xff\x7f")) == -1);
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testing.expect((try test_read_ileb128(i32, "\xff\xff\xff\xff\x7f")) == -1);
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testing.expect((try test_read_ileb128(i32, "\x80\x80\x80\x80\x08")) == -0x80000000);
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testing.expect((try test_read_ileb128(i64, "\x80\x80\x80\x80\x80\x80\x80\x80\x80\x01")) == @bitCast(i64, @intCast(u64, 0x8000000000000000)));
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testing.expect((try test_read_ileb128(i64, "\x80\x80\x80\x80\x80\x80\x80\x80\x40")) == -0x4000000000000000);
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testing.expect((try test_read_ileb128(i64, "\x80\x80\x80\x80\x80\x80\x80\x80\x80\x7f")) == -0x8000000000000000);
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// Decode unnormalized SLEB128 with extra padding bytes.
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testing.expect((try test_read_ileb128(i64, "\x80\x00")) == 0);
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testing.expect((try test_read_ileb128(i64, "\x80\x80\x00")) == 0);
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testing.expect((try test_read_ileb128(i64, "\xff\x00")) == 0x7f);
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testing.expect((try test_read_ileb128(i64, "\xff\x80\x00")) == 0x7f);
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testing.expect((try test_read_ileb128(i64, "\x80\x81\x00")) == 0x80);
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testing.expect((try test_read_ileb128(i64, "\x80\x81\x80\x00")) == 0x80);
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// Decode sequence of SLEB128 values
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test_read_ileb128_seq(i64, 4, "\x81\x01\x3f\x80\x7f\x80\x80\x80\x00");
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}
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test "deserialize unsigned LEB128" {
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// Truncated
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testing.expectError(error.EndOfStream, test_read_stream_uleb128(u64, "\x80"));
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// Overflow
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testing.expectError(error.Overflow, test_read_uleb128(u8, "\x80\x02"));
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testing.expectError(error.Overflow, test_read_uleb128(u8, "\x80\x80\x40"));
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testing.expectError(error.Overflow, test_read_uleb128(u16, "\x80\x80\x84"));
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testing.expectError(error.Overflow, test_read_uleb128(u16, "\x80\x80\x80\x40"));
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testing.expectError(error.Overflow, test_read_uleb128(u32, "\x80\x80\x80\x80\x90"));
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testing.expectError(error.Overflow, test_read_uleb128(u32, "\x80\x80\x80\x80\x40"));
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testing.expectError(error.Overflow, test_read_uleb128(u64, "\x80\x80\x80\x80\x80\x80\x80\x80\x80\x40"));
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// Decode ULEB128
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testing.expect((try test_read_uleb128(u64, "\x00")) == 0);
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testing.expect((try test_read_uleb128(u64, "\x01")) == 1);
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testing.expect((try test_read_uleb128(u64, "\x3f")) == 63);
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testing.expect((try test_read_uleb128(u64, "\x40")) == 64);
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testing.expect((try test_read_uleb128(u64, "\x7f")) == 0x7f);
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testing.expect((try test_read_uleb128(u64, "\x80\x01")) == 0x80);
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testing.expect((try test_read_uleb128(u64, "\x81\x01")) == 0x81);
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testing.expect((try test_read_uleb128(u64, "\x90\x01")) == 0x90);
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testing.expect((try test_read_uleb128(u64, "\xff\x01")) == 0xff);
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testing.expect((try test_read_uleb128(u64, "\x80\x02")) == 0x100);
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testing.expect((try test_read_uleb128(u64, "\x81\x02")) == 0x101);
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testing.expect((try test_read_uleb128(u64, "\x80\xc1\x80\x80\x10")) == 4294975616);
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testing.expect((try test_read_uleb128(u64, "\x80\x80\x80\x80\x80\x80\x80\x80\x80\x01")) == 0x8000000000000000);
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// Decode ULEB128 with extra padding bytes
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testing.expect((try test_read_uleb128(u64, "\x80\x00")) == 0);
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testing.expect((try test_read_uleb128(u64, "\x80\x80\x00")) == 0);
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testing.expect((try test_read_uleb128(u64, "\xff\x00")) == 0x7f);
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testing.expect((try test_read_uleb128(u64, "\xff\x80\x00")) == 0x7f);
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testing.expect((try test_read_uleb128(u64, "\x80\x81\x00")) == 0x80);
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testing.expect((try test_read_uleb128(u64, "\x80\x81\x80\x00")) == 0x80);
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// Decode sequence of ULEB128 values
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test_read_uleb128_seq(u64, 4, "\x81\x01\x3f\x80\x7f\x80\x80\x80\x00");
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}
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