diff --git a/std/special/compiler_rt/floatuntitf.zig b/std/special/compiler_rt/floatuntitf.zig new file mode 100644 index 0000000000..a64dd96a34 --- /dev/null +++ b/std/special/compiler_rt/floatuntitf.zig @@ -0,0 +1,60 @@ +const builtin = @import("builtin"); +const is_test = builtin.is_test; + +const LDBL_MANT_DIG = 113; + +pub extern fn __floatuntitf(arg: u128) f128 { + @setRuntimeSafety(is_test); + + if (arg == 0) + return 0.0; + + var a = arg; + const N: u32 = @sizeOf(u128) * 8; + const sd = @bitCast(i32, N -% @clz(a)); // number of significant digits + var e: i32 = sd -% 1; // exponent + if (sd > LDBL_MANT_DIG) { + // start: 0000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQxxxxxxxxxxxxxxxxxx + // finish: 000000000000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQR + // 12345678901234567890123456 + // 1 = msb 1 bit + // P = bit LDBL_MANT_DIG-1 bits to the right of 1 + // Q = bit LDBL_MANT_DIG bits to the right of 1 + // R = "or" of all bits to the right of Q + switch (sd) { + LDBL_MANT_DIG + 1 => { + a <<= 1; + }, + LDBL_MANT_DIG + 2 => {}, + else => { + const shift_amt = @bitCast(i32, N +% (LDBL_MANT_DIG + 2)) -% sd; + const shift_amt_u7 = @intCast(u7, shift_amt); + a = (a >> @intCast(u7, sd -% (LDBL_MANT_DIG + 2))) | + @boolToInt((a & (u128(@maxValue(u128)) >> shift_amt_u7)) != 0); + }, + } + // finish + a |= @boolToInt((a & 4) != 0); // Or P into R + a +%= 1; // round - this step may add a significant bit + a >>= 2; // dump Q and R + // a is now rounded to LDBL_MANT_DIG or LDBL_MANT_DIG+1 bits + if ((a & (u128(1) << LDBL_MANT_DIG)) != 0) { + a >>= 1; + e +%= 1; + } + // a is now rounded to LDBL_MANT_DIG bits + } else { + a <<= @intCast(u7, LDBL_MANT_DIG -% sd); + // a is now rounded to LDBL_MANT_DIG bits + } + + const high: u128 = (@intCast(u64, (e +% 16383)) << 48) | // exponent + (@truncate(u64, a >> 64) & 0x0000ffffffffffff); // mantissa-high + const low = @truncate(u64, a); // mantissa-low + + return @bitCast(f128, low | (high << 64)); +} + +test "import floatuntitf" { + _ = @import("floatuntitf_test.zig"); +} diff --git a/std/special/compiler_rt/floatuntitf_test.zig b/std/special/compiler_rt/floatuntitf_test.zig new file mode 100644 index 0000000000..8e67fee108 --- /dev/null +++ b/std/special/compiler_rt/floatuntitf_test.zig @@ -0,0 +1,99 @@ +const __floatuntitf = @import("floatuntitf.zig").__floatuntitf; +const assert = @import("std").debug.assert; + +fn test__floatuntitf(a: u128, expected: f128) void { + const x = __floatuntitf(a); + assert(x == expected); +} + +test "floatuntitf" { + test__floatuntitf(0, 0.0); + + test__floatuntitf(1, 1.0); + test__floatuntitf(2, 2.0); + test__floatuntitf(20, 20.0); + + test__floatuntitf(0x7FFFFF8000000000, 0x1.FFFFFEp+62); + test__floatuntitf(0x7FFFFFFFFFFFF800, 0x1.FFFFFFFFFFFFEp+62); + test__floatuntitf(0x7FFFFF0000000000, 0x1.FFFFFCp+62); + test__floatuntitf(0x7FFFFFFFFFFFF000, 0x1.FFFFFFFFFFFFCp+62); + test__floatuntitf(0x7FFFFFFFFFFFFFFF, 0xF.FFFFFFFFFFFFFFEp+59); + test__floatuntitf(0xFFFFFFFFFFFFFFFE, 0xF.FFFFFFFFFFFFFFEp+60); + test__floatuntitf(0xFFFFFFFFFFFFFFFF, 0xF.FFFFFFFFFFFFFFFp+60); + + test__floatuntitf(0x8000008000000000, 0x8.000008p+60); + test__floatuntitf(0x8000000000000800, 0x8.0000000000008p+60); + test__floatuntitf(0x8000010000000000, 0x8.00001p+60); + test__floatuntitf(0x8000000000001000, 0x8.000000000001p+60); + + test__floatuntitf(0x8000000000000000, 0x8p+60); + test__floatuntitf(0x8000000000000001, 0x8.000000000000001p+60); + + test__floatuntitf(0x0007FB72E8000000, 0x1.FEDCBAp+50); + + test__floatuntitf(0x0007FB72EA000000, 0x1.FEDCBA8p+50); + test__floatuntitf(0x0007FB72EB000000, 0x1.FEDCBACp+50); + test__floatuntitf(0x0007FB72EBFFFFFF, 0x1.FEDCBAFFFFFFCp+50); + test__floatuntitf(0x0007FB72EC000000, 0x1.FEDCBBp+50); + test__floatuntitf(0x0007FB72E8000001, 0x1.FEDCBA0000004p+50); + + test__floatuntitf(0x0007FB72E6000000, 0x1.FEDCB98p+50); + test__floatuntitf(0x0007FB72E7000000, 0x1.FEDCB9Cp+50); + test__floatuntitf(0x0007FB72E7FFFFFF, 0x1.FEDCB9FFFFFFCp+50); + test__floatuntitf(0x0007FB72E4000001, 0x1.FEDCB90000004p+50); + test__floatuntitf(0x0007FB72E4000000, 0x1.FEDCB9p+50); + + test__floatuntitf(0x023479FD0E092DC0, 0x1.1A3CFE870496Ep+57); + test__floatuntitf(0x023479FD0E092DA1, 0x1.1A3CFE870496D08p+57); + test__floatuntitf(0x023479FD0E092DB0, 0x1.1A3CFE870496D8p+57); + test__floatuntitf(0x023479FD0E092DB8, 0x1.1A3CFE870496DCp+57); + test__floatuntitf(0x023479FD0E092DB6, 0x1.1A3CFE870496DBp+57); + test__floatuntitf(0x023479FD0E092DBF, 0x1.1A3CFE870496DF8p+57); + test__floatuntitf(0x023479FD0E092DC1, 0x1.1A3CFE870496E08p+57); + test__floatuntitf(0x023479FD0E092DC7, 0x1.1A3CFE870496E38p+57); + test__floatuntitf(0x023479FD0E092DC8, 0x1.1A3CFE870496E4p+57); + test__floatuntitf(0x023479FD0E092DCF, 0x1.1A3CFE870496E78p+57); + test__floatuntitf(0x023479FD0E092DD0, 0x1.1A3CFE870496E8p+57); + test__floatuntitf(0x023479FD0E092DD1, 0x1.1A3CFE870496E88p+57); + test__floatuntitf(0x023479FD0E092DD8, 0x1.1A3CFE870496ECp+57); + test__floatuntitf(0x023479FD0E092DDF, 0x1.1A3CFE870496EF8p+57); + test__floatuntitf(0x023479FD0E092DE0, 0x1.1A3CFE870496Fp+57); + + test__floatuntitf(make_ti(0x023479FD0E092DC0, 0), 0x1.1A3CFE870496Ep+121); + test__floatuntitf(make_ti(0x023479FD0E092DA1, 1), 0x1.1A3CFE870496D08p+121); + test__floatuntitf(make_ti(0x023479FD0E092DB0, 2), 0x1.1A3CFE870496D8p+121); + test__floatuntitf(make_ti(0x023479FD0E092DB8, 3), 0x1.1A3CFE870496DCp+121); + test__floatuntitf(make_ti(0x023479FD0E092DB6, 4), 0x1.1A3CFE870496DBp+121); + test__floatuntitf(make_ti(0x023479FD0E092DBF, 5), 0x1.1A3CFE870496DF8p+121); + test__floatuntitf(make_ti(0x023479FD0E092DC1, 6), 0x1.1A3CFE870496E08p+121); + test__floatuntitf(make_ti(0x023479FD0E092DC7, 7), 0x1.1A3CFE870496E38p+121); + test__floatuntitf(make_ti(0x023479FD0E092DC8, 8), 0x1.1A3CFE870496E4p+121); + test__floatuntitf(make_ti(0x023479FD0E092DCF, 9), 0x1.1A3CFE870496E78p+121); + test__floatuntitf(make_ti(0x023479FD0E092DD0, 0), 0x1.1A3CFE870496E8p+121); + test__floatuntitf(make_ti(0x023479FD0E092DD1, 11), 0x1.1A3CFE870496E88p+121); + test__floatuntitf(make_ti(0x023479FD0E092DD8, 12), 0x1.1A3CFE870496ECp+121); + test__floatuntitf(make_ti(0x023479FD0E092DDF, 13), 0x1.1A3CFE870496EF8p+121); + test__floatuntitf(make_ti(0x023479FD0E092DE0, 14), 0x1.1A3CFE870496Fp+121); + + test__floatuntitf(make_ti(0, 0xFFFFFFFFFFFFFFFF), 0x1.FFFFFFFFFFFFFFFEp+63); + + test__floatuntitf(make_ti(0xFFFFFFFFFFFFFFFF, 0x0000000000000000), 0x1.FFFFFFFFFFFFFFFEp+127); + test__floatuntitf(make_ti(0xFFFFFFFFFFFFFFFF, 0xFFFFFFFFFFFFFFFF), 0x1.0000000000000000p+128); + + test__floatuntitf(make_ti(0x123456789ABCDEF0, 0x123456789ABC2801), 0x1.23456789ABCDEF0123456789ABC3p+124); + test__floatuntitf(make_ti(0x123456789ABCDEF0, 0x123456789ABC3000), 0x1.23456789ABCDEF0123456789ABC3p+124); + test__floatuntitf(make_ti(0x123456789ABCDEF0, 0x123456789ABC37FF), 0x1.23456789ABCDEF0123456789ABC3p+124); + test__floatuntitf(make_ti(0x123456789ABCDEF0, 0x123456789ABC3800), 0x1.23456789ABCDEF0123456789ABC4p+124); + test__floatuntitf(make_ti(0x123456789ABCDEF0, 0x123456789ABC4000), 0x1.23456789ABCDEF0123456789ABC4p+124); + test__floatuntitf(make_ti(0x123456789ABCDEF0, 0x123456789ABC47FF), 0x1.23456789ABCDEF0123456789ABC4p+124); + test__floatuntitf(make_ti(0x123456789ABCDEF0, 0x123456789ABC4800), 0x1.23456789ABCDEF0123456789ABC4p+124); + test__floatuntitf(make_ti(0x123456789ABCDEF0, 0x123456789ABC4801), 0x1.23456789ABCDEF0123456789ABC5p+124); + test__floatuntitf(make_ti(0x123456789ABCDEF0, 0x123456789ABC57FF), 0x1.23456789ABCDEF0123456789ABC5p+124); +} + +fn make_ti(high: u64, low: u64) u128 { + var result: u128 = high; + result <<= 64; + result |= low; + return result; +}