From: Bastian Koppelmann <kbastian@mail.uni-paderborn.de>
To: qemu-devel@nongnu.org
Cc: sw@weilnetz.de
Subject: [Qemu-devel] [PATCH] target-tricore: properly fix dvinit_b/h_13
Date: Mon, 23 Mar 2015 18:37:05 +0100 [thread overview]
Message-ID: <1427132225-18863-1-git-send-email-kbastian@mail.uni-paderborn.de> (raw)
The TriCore documentation was wrong on how to calculate ovf bits for those two
instructions, which I confirmed with real hardware (TC1796 chip). An ovf
actually happens, if the result (without remainder) does not fit into 8/16 bits.
Signed-off-by: Bastian Koppelmann <kbastian@mail.uni-paderborn.de>
---
target-tricore/op_helper.c | 40 ++++++++++------------------------------
1 file changed, 10 insertions(+), 30 deletions(-)
diff --git a/target-tricore/op_helper.c b/target-tricore/op_helper.c
index 2cfa95d..220ec4a 100644
--- a/target-tricore/op_helper.c
+++ b/target-tricore/op_helper.c
@@ -1942,29 +1942,19 @@ uint64_t helper_unpack(target_ulong arg1)
uint64_t helper_dvinit_b_13(CPUTriCoreState *env, uint32_t r1, uint32_t r2)
{
uint64_t ret;
- int32_t abs_sig_dividend, abs_base_dividend, abs_divisor;
- int32_t quotient_sign;
+ int32_t abs_sig_dividend, abs_divisor;
ret = sextract32(r1, 0, 32);
ret = ret << 24;
- quotient_sign = 0;
if (!((r1 & 0x80000000) == (r2 & 0x80000000))) {
ret |= 0xffffff;
- quotient_sign = 1;
}
- abs_sig_dividend = abs((int32_t)r1) >> 7;
- abs_base_dividend = abs((int32_t)r1) & 0x7f;
+ abs_sig_dividend = abs((int32_t)r1) >> 8;
abs_divisor = abs((int32_t)r2);
- /* calc overflow */
- env->PSW_USB_V = 0;
- if ((quotient_sign) && (abs_divisor)) {
- env->PSW_USB_V = (((abs_sig_dividend == abs_divisor) &&
- (abs_base_dividend >= abs_divisor)) ||
- (abs_sig_dividend > abs_divisor));
- } else {
- env->PSW_USB_V = (abs_sig_dividend >= abs_divisor);
- }
+ /* calc overflow
+ ofv if (a/b >= 255) <=> (a/255 >= b) */
+ env->PSW_USB_V = (abs_sig_dividend >= abs_divisor) << 31;
env->PSW_USB_V = env->PSW_USB_V << 31;
env->PSW_USB_SV |= env->PSW_USB_V;
env->PSW_USB_AV = 0;
@@ -1992,29 +1982,19 @@ uint64_t helper_dvinit_b_131(CPUTriCoreState *env, uint32_t r1, uint32_t r2)
uint64_t helper_dvinit_h_13(CPUTriCoreState *env, uint32_t r1, uint32_t r2)
{
uint64_t ret;
- int32_t abs_sig_dividend, abs_base_dividend, abs_divisor;
- int32_t quotient_sign;
+ int32_t abs_sig_dividend, abs_divisor;
ret = sextract32(r1, 0, 32);
ret = ret << 16;
- quotient_sign = 0;
if (!((r1 & 0x80000000) == (r2 & 0x80000000))) {
ret |= 0xffff;
- quotient_sign = 1;
}
- abs_sig_dividend = abs((int32_t)r1) >> 7;
- abs_base_dividend = abs((int32_t)r1) & 0x7f;
+ abs_sig_dividend = abs((int32_t)r1) >> 16;
abs_divisor = abs((int32_t)r2);
- /* calc overflow */
- env->PSW_USB_V = 0;
- if ((quotient_sign) && (abs_divisor)) {
- env->PSW_USB_V = (((abs_sig_dividend == abs_divisor) &&
- (abs_base_dividend >= abs_divisor)) ||
- (abs_sig_dividend > abs_divisor));
- } else {
- env->PSW_USB_V = (abs_sig_dividend >= abs_divisor);
- }
+ /* calc overflow
+ ofv if (a/b >= 0xffff) <=> (a/0xffff >= b) */
+ env->PSW_USB_V = (abs_sig_dividend >= abs_divisor) << 31;
env->PSW_USB_V = env->PSW_USB_V << 31;
env->PSW_USB_SV |= env->PSW_USB_V;
env->PSW_USB_AV = 0;
--
2.3.3
reply other threads:[~2015-03-23 16:35 UTC|newest]
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