cleanup and microoptimizations in SH2 hw handling

cpu/drc/emit_arm64.c

@@ -1163,9 +1163,10 @@ static void emith_ldst_offs(int sz, int rd, int rn, int o9, int ld, int mode)
 	int t2 = rcache_get_tmp();				\
 	int t3 = rcache_get_tmp();				\
 	/* if (sr < 0) return */				\
-	emith_asrf(t2, sr, 12);					\
+	emith_cmp_r_imm(sr, 0);					\
 	EMITH_JMP_START(DCOND_LE);				\
 	/* turns = sr.cycles / cycles */			\
+	emith_asr(t2, sr, 12);					\
 	emith_move_r_imm(t3, (u32)((1ULL<<32) / (cycles)) + 1);	\
 	emith_mul_u64(t1, t2, t2, t3); /* multiply by 1/x */	\
 	rcache_free_tmp(t3);					\

cpu/drc/emit_mips.c

@@ -560,8 +560,8 @@ static void emith_set_arith_flags(int rd, int rt, int rs, s32 imm, int sub)
 #define emith_adc_r_r(d, s) \
 	emith_adc_r_r_r(d, d, s)
 
-// NB: the incoming C can cause its own outgoing C if s2+C=0 (or s1+C=0 FWIW)
-// moreover, s2 is 0 if there is C, so no other C can be generated.
+// NB: the incoming carry Cin can cause Cout if s2+Cin=0 (or s1+Cin=0 FWIW)
+// moreover, if s2+Cin=0 caused Cout, s1+s2+Cin=s1+0 can't cause another Cout
 #define emith_adcf_r_r_r(d, s1, s2) do { \
 	emith_add_r_r_r(FNZ, s2, FC); \
 	EMIT(MIPS_SLTU_REG(AT, FNZ, FC)); \

cpu/drc/emit_x86.c

@@ -1,7 +1,7 @@
 /*
  * Basic macros to emit x86 instructions and some utils
  * Copyright (C) 2008,2009,2010 notaz
- * Copyright (C) 2019 kuv
+ * Copyright (C) 2019 kub
  *
  * This work is licensed under the terms of MAME license.
  * See COPYING file in the top-level directory.