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authorLaurent Vivier <laurent@vivier.eu>2018-03-05 21:39:07 +0100
committerLaurent Vivier <laurent@vivier.eu>2018-03-09 15:50:38 +0100
commit67b453ed73fe65949c24e6ca2b43f6816a89a301 (patch)
tree29dedbbff941898a4ec0f97422ff2b8e28377505 /target/m68k
parent248efb66fb88bc17c04a0d0f09a3539a43c80769 (diff)
target/m68k: implement flog2
Using a local m68k floatx80_log2() [copied from previous: Written by Andreas Grabher for Previous, NeXT Computer Emulator.] Signed-off-by: Laurent Vivier <laurent@vivier.eu> Message-Id: <20180305203910.10391-6-laurent@vivier.eu>
Diffstat (limited to 'target/m68k')
-rw-r--r--target/m68k/fpu_helper.c5
-rw-r--r--target/m68k/helper.h1
-rw-r--r--target/m68k/softfloat.c67
-rw-r--r--target/m68k/softfloat.h1
-rw-r--r--target/m68k/translate.c3
5 files changed, 77 insertions, 0 deletions
diff --git a/target/m68k/fpu_helper.c b/target/m68k/fpu_helper.c
index 2628534136..97a4501126 100644
--- a/target/m68k/fpu_helper.c
+++ b/target/m68k/fpu_helper.c
@@ -572,3 +572,8 @@ void HELPER(flog10)(CPUM68KState *env, FPReg *res, FPReg *val)
{
res->d = floatx80_log10(val->d, &env->fp_status);
}
+
+void HELPER(flog2)(CPUM68KState *env, FPReg *res, FPReg *val)
+{
+ res->d = floatx80_log2(val->d, &env->fp_status);
+}
diff --git a/target/m68k/helper.h b/target/m68k/helper.h
index d1f38f260f..15f63b353f 100644
--- a/target/m68k/helper.h
+++ b/target/m68k/helper.h
@@ -71,6 +71,7 @@ DEF_HELPER_4(fscale, void, env, fp, fp, fp)
DEF_HELPER_3(flognp1, void, env, fp, fp)
DEF_HELPER_3(flogn, void, env, fp, fp)
DEF_HELPER_3(flog10, void, env, fp, fp)
+DEF_HELPER_3(flog2, void, env, fp, fp)
DEF_HELPER_3(mac_move, void, env, i32, i32)
DEF_HELPER_3(macmulf, i64, env, i32, i32)
diff --git a/target/m68k/softfloat.c b/target/m68k/softfloat.c
index 22fd7f6341..9fa6d6fd05 100644
--- a/target/m68k/softfloat.c
+++ b/target/m68k/softfloat.c
@@ -715,3 +715,70 @@ floatx80 floatx80_log10(floatx80 a, float_status *status)
return a;
}
+
+/*----------------------------------------------------------------------------
+ | Log base 2
+ *----------------------------------------------------------------------------*/
+
+floatx80 floatx80_log2(floatx80 a, float_status *status)
+{
+ flag aSign;
+ int32_t aExp;
+ uint64_t aSig;
+
+ int8_t user_rnd_mode, user_rnd_prec;
+
+ floatx80 fp0, fp1;
+
+ aSig = extractFloatx80Frac(a);
+ aExp = extractFloatx80Exp(a);
+ aSign = extractFloatx80Sign(a);
+
+ if (aExp == 0x7FFF) {
+ if ((uint64_t) (aSig << 1)) {
+ propagateFloatx80NaNOneArg(a, status);
+ }
+ if (aSign == 0) {
+ return packFloatx80(0, floatx80_infinity.high,
+ floatx80_infinity.low);
+ }
+ }
+
+ if (aExp == 0) {
+ if (aSig == 0) {
+ float_raise(float_flag_divbyzero, status);
+ return packFloatx80(1, floatx80_infinity.high,
+ floatx80_infinity.low);
+ }
+ normalizeFloatx80Subnormal(aSig, &aExp, &aSig);
+ }
+
+ if (aSign) {
+ float_raise(float_flag_invalid, status);
+ return floatx80_default_nan(status);
+ }
+
+ user_rnd_mode = status->float_rounding_mode;
+ user_rnd_prec = status->floatx80_rounding_precision;
+ status->float_rounding_mode = float_round_nearest_even;
+ status->floatx80_rounding_precision = 80;
+
+ if (aSig == one_sig) { /* X is 2^k */
+ status->float_rounding_mode = user_rnd_mode;
+ status->floatx80_rounding_precision = user_rnd_prec;
+
+ a = int32_to_floatx80(aExp - 0x3FFF, status);
+ } else {
+ fp0 = floatx80_logn(a, status);
+ fp1 = packFloatx80(0, 0x3FFF, LIT64(0xB8AA3B295C17F0BC)); /* INV_L2 */
+
+ status->float_rounding_mode = user_rnd_mode;
+ status->floatx80_rounding_precision = user_rnd_prec;
+
+ a = floatx80_mul(fp0, fp1, status); /* LOGN(X)*INV_L2 */
+ }
+
+ float_raise(float_flag_inexact, status);
+
+ return a;
+}
diff --git a/target/m68k/softfloat.h b/target/m68k/softfloat.h
index ac29e76189..c0b77cf01b 100644
--- a/target/m68k/softfloat.h
+++ b/target/m68k/softfloat.h
@@ -30,4 +30,5 @@ floatx80 floatx80_move(floatx80 a, float_status *status);
floatx80 floatx80_lognp1(floatx80 a, float_status *status);
floatx80 floatx80_logn(floatx80 a, float_status *status);
floatx80 floatx80_log10(floatx80 a, float_status *status);
+floatx80 floatx80_log2(floatx80 a, float_status *status);
#endif
diff --git a/target/m68k/translate.c b/target/m68k/translate.c
index f1130df314..189b23d38d 100644
--- a/target/m68k/translate.c
+++ b/target/m68k/translate.c
@@ -5063,6 +5063,9 @@ DISAS_INSN(fpu)
case 0x15: /* flog10 */
gen_helper_flog10(cpu_env, cpu_dest, cpu_src);
break;
+ case 0x16: /* flog2 */
+ gen_helper_flog2(cpu_env, cpu_dest, cpu_src);
+ break;
case 0x18: /* fabs */
gen_helper_fabs(cpu_env, cpu_dest, cpu_src);
break;