| author |  Marc Tiehuis <marc@tiehu.is> 2018-06-28 20:12:03+12:00 |
| committer | Marc Tiehuis <marc@tiehu.is> 2018-06-28 20:12:03+12:00 |
| log | 4a35d7eeebec3f345e2482bc189f07c19dcf6f8b |
| tree | c83abddc3c635fb9daa4ff9b85ebf19a341948d2 |
| parent | 2fa588e81d60cfe319446bd0483c6bf296f40c40 |
Correct hex-float parsing
Unblocks #495.2 files changed, 17 insertions(+), 2 deletions(-)
test- cases
src/tokenizer.cpp+9-2
| ... | @@ -357,12 +357,19 @@ static void end_float_token(Tokenize *t) { | ... | @@ -357,12 +357,19 @@ static void end_float_token(Tokenize *t) { |
| 357 | // Mask the sign bit to 0 since always non-negative lex | 357 | // Mask the sign bit to 0 since always non-negative lex |
| 358 | const uint64_t exp_mask = 0xffffull << exp_shift; | 358 | const uint64_t exp_mask = 0xffffull << exp_shift; |
| 359 | 359 | ||
| 360 | if (shift >= 64) { | 360 | // must be special-cased to avoid undefined behavior on shift == 64 |
| 361 | if (shift == 128) { | ||
| 362 | f_bits.repr[0] = 0; | ||
| 363 | f_bits.repr[1] = sig_bits[0]; | ||
| 364 | } else if (shift == 0) { | ||
| 365 | f_bits.repr[0] = sig_bits[0]; | ||
| 366 | f_bits.repr[1] = sig_bits[1]; | ||
| 367 | } else if (shift >= 64) { | ||
| 361 | f_bits.repr[0] = 0; | 368 | f_bits.repr[0] = 0; |
| 362 | f_bits.repr[1] = sig_bits[0] << (shift - 64); | 369 | f_bits.repr[1] = sig_bits[0] << (shift - 64); |
| 363 | } else { | 370 | } else { |
| 364 | f_bits.repr[0] = sig_bits[0] << shift; | 371 | f_bits.repr[0] = sig_bits[0] << shift; |
| 365 | f_bits.repr[1] = ((sig_bits[1] << shift) | (sig_bits[0] >> (64 - shift))); | 372 | f_bits.repr[1] = (sig_bits[1] << shift) | (sig_bits[0] >> (64 - shift)); |
| 366 | } | 373 | } |
| 367 | 374 | ||
| 368 | f_bits.repr[1] &= ~exp_mask; | 375 | f_bits.repr[1] &= ~exp_mask; |
test/cases/math.zig+8
| ... | @@ -296,6 +296,14 @@ test "quad hex float literal parsing in range" { | ... | @@ -296,6 +296,14 @@ test "quad hex float literal parsing in range" { |
| 296 | const d = 0x1.edcbff8ad76ab5bf46463233214fp-435; | 296 | const d = 0x1.edcbff8ad76ab5bf46463233214fp-435; |
| 297 | } | 297 | } |
| 298 | 298 | ||
| 299 | test "quad hex float literal parsing accurate" { | ||
| 300 | const a: f128 = 0x1.1111222233334444555566667777p+0; | ||
| 301 | |||
| 302 | // implied 1 is dropped, with an exponent of 0 (0x3fff) after biasing. | ||
| 303 | const expected: u128 = 0x3fff1111222233334444555566667777; | ||
| 304 | assert(@bitCast(u128, a) == expected); | ||
| 305 | } | ||
| 306 | |||
| 299 | test "hex float literal within range" { | 307 | test "hex float literal within range" { |
| 300 | const a = 0x1.0p16383; | 308 | const a = 0x1.0p16383; |
| 301 | const b = 0x0.1p16387; | 309 | const b = 0x0.1p16387; |