diff options
author | Alex Bennée <alex.bennee@linaro.org> | 2014-03-17 16:31:50 +0000 |
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committer | Peter Maydell <peter.maydell@linaro.org> | 2014-03-17 16:31:50 +0000 |
commit | 8f0c6758b0e1c3b9676e7c3ccea8a176537cf843 (patch) | |
tree | fb94230a002c91f6b77badbe084b7675f169a14f /target-arm/helper-a64.c | |
parent | a566da1b02704a79038043ddbe850f40b033cd63 (diff) |
target-arm: A64: Add FRECPX (reciprocal exponent)
These are fairly simple exponent only estimation functions using helpers.
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Message-id: 1394822294-14837-14-git-send-email-peter.maydell@linaro.org
Diffstat (limited to 'target-arm/helper-a64.c')
-rw-r--r-- | target-arm/helper-a64.c | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/target-arm/helper-a64.c b/target-arm/helper-a64.c index c31c45e729..cea2468b30 100644 --- a/target-arm/helper-a64.c +++ b/target-arm/helper-a64.c @@ -354,3 +354,62 @@ uint64_t HELPER(neon_addlp_u16)(uint64_t a) tmp += (a >> 16) & 0x0000ffff0000ffffULL; return tmp; } + +/* Floating-point reciprocal exponent - see FPRecpX in ARM ARM */ +float32 HELPER(frecpx_f32)(float32 a, void *fpstp) +{ + float_status *fpst = fpstp; + uint32_t val32, sbit; + int32_t exp; + + if (float32_is_any_nan(a)) { + float32 nan = a; + if (float32_is_signaling_nan(a)) { + float_raise(float_flag_invalid, fpst); + nan = float32_maybe_silence_nan(a); + } + if (fpst->default_nan_mode) { + nan = float32_default_nan; + } + return nan; + } + + val32 = float32_val(a); + sbit = 0x80000000ULL & val32; + exp = extract32(val32, 23, 8); + + if (exp == 0) { + return make_float32(sbit | (0xfe << 23)); + } else { + return make_float32(sbit | (~exp & 0xff) << 23); + } +} + +float64 HELPER(frecpx_f64)(float64 a, void *fpstp) +{ + float_status *fpst = fpstp; + uint64_t val64, sbit; + int64_t exp; + + if (float64_is_any_nan(a)) { + float64 nan = a; + if (float64_is_signaling_nan(a)) { + float_raise(float_flag_invalid, fpst); + nan = float64_maybe_silence_nan(a); + } + if (fpst->default_nan_mode) { + nan = float64_default_nan; + } + return nan; + } + + val64 = float64_val(a); + sbit = 0x8000000000000000ULL & val64; + exp = extract64(float64_val(a), 52, 11); + + if (exp == 0) { + return make_float64(sbit | (0x7feULL << 52)); + } else { + return make_float64(sbit | (~exp & 0x7ffULL) << 52); + } +} |