diff options
| author | Petar Jovanovic <petar.jovanovic@imgtec.com> | 2013-07-01 01:54:47 +0200 |
|---|---|---|
| committer | Aurelien Jarno <aurelien@aurel32.net> | 2013-07-29 00:27:36 +0200 |
| commit | d36c231f4b7386bd8230aa17d362b925aa419b2f (patch) | |
| tree | 49513570a018c658582d8fb24b88bb8487988489 /target-mips | |
| parent | 05b3274b6bedb68ff78b76c642e17e97f3181c2f (diff) | |
| download | qemu-d36c231f4b7386bd8230aa17d362b925aa419b2f.tar.gz | |
target-mips: fix mipsdsp_trunc16_sat16_round
This change corrects rounding and saturation of Q31 fractional value in
mipsdsp_trunc16_sat16_round(). Overflow detection was incorrect for the
corner case for PRECRQ_RS.PH, and this test case is also part of the change.
Signed-off-by: Petar Jovanovic <petar.jovanovic@imgtec.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Diffstat (limited to 'target-mips')
| -rw-r--r-- | target-mips/dsp_helper.c | 16 |
1 files changed, 11 insertions, 5 deletions
diff --git a/target-mips/dsp_helper.c b/target-mips/dsp_helper.c index c718a786e1..93f5d9e023 100644 --- a/target-mips/dsp_helper.c +++ b/target-mips/dsp_helper.c @@ -648,16 +648,22 @@ static inline int32_t mipsdsp_sat16_mul_q15_q15(uint16_t a, uint16_t b, static inline uint16_t mipsdsp_trunc16_sat16_round(int32_t a, CPUMIPSState *env) { - int64_t temp; + uint16_t temp; - temp = (int32_t)a + 0x00008000; - if (a > (int)0x7fff8000) { - temp = 0x7FFFFFFF; + /* + * The value 0x00008000 will be added to the input Q31 value, and the code + * needs to check if the addition causes an overflow. Since a positive value + * is added, overflow can happen in one direction only. + */ + if (a > 0x7FFF7FFF) { + temp = 0x7FFF; set_DSPControl_overflow_flag(1, 22, env); + } else { + temp = ((a + 0x8000) >> 16) & 0xFFFF; } - return (temp >> 16) & 0xFFFF; + return temp; } static inline uint8_t mipsdsp_sat8_reduce_precision(uint16_t a, |