Re: [Qemu-devel] [PATCH 04/16] target-m68k: add scc/dbcc

[Richard Henderson]

On 10/26/2016 09:35 AM, Laurent Vivier wrote:
Signed-off-by: Laurent Vivier <laur...@vivier.eu>
---
 target-m68k/translate.c | 65 ++++++++++++++++++++++++++++++++++---------------
 1 file changed, 45 insertions(+), 20 deletions(-)
diff --git a/target-m68k/translate.c b/target-m68k/translate.c
index a07b6f5..05efd29 100644
--- a/target-m68k/translate.c
+++ b/target-m68k/translate.c
@@ -1008,25 +1008,6 @@ static void gen_jmpcc(DisasContext *s, int cond, 
TCGLabel *l1)
   free_cond(&c);
 }

-DISAS_INSN(scc)
-{
-    DisasCompare c;
-    int cond;
-    TCGv reg, tmp;
-
-    cond = (insn >> 8) & 0xf;
-    gen_cc_cond(&c, s, cond);
-
-    tmp = tcg_temp_new();
-    tcg_gen_setcond_i32(c.tcond, tmp, c.v1, c.v2);
-    free_cond(&c);
-
-    reg = DREG(insn, 0);
-    tcg_gen_neg_i32(tmp, tmp);
-    tcg_gen_deposit_i32(reg, reg, tmp, 0, 8);
-    tcg_temp_free(tmp);
-}
-
 /* Force a TB lookup after an instruction that changes the CPU state.  */
 static void gen_lookup_tb(DisasContext *s)
 {
@@ -1106,6 +1087,48 @@ static void gen_jmp_tb(DisasContext *s, int n, uint32_t 
dest)
     s->is_jmp = DISAS_TB_JUMP;
 }

+DISAS_INSN(scc)
+{
+    DisasCompare c;
+    int cond;
+    TCGv tmp;
+
+    cond = (insn >> 8) & 0xf;
+    gen_cc_cond(&c, s, cond);
+
+    tmp = tcg_temp_new();
+    tcg_gen_setcond_i32(c.tcond, tmp, c.v1, c.v2);
+    free_cond(&c);
+
+    tcg_gen_neg_i32(tmp, tmp);
+    DEST_EA(env, insn, OS_BYTE, tmp, NULL);
+    tcg_temp_free(tmp);
+}

This change to scc, to add support for EA, should be in a separate patch from 
adding dbcc.  Otherwise it looks good.


r~


+
+DISAS_INSN(dbcc)
+{
+    TCGLabel *l1;
+    TCGv reg;
+    TCGv tmp;
+    int16_t offset;
+    uint32_t base;
+
+    reg = DREG(insn, 0);
+    base = s->pc;
+    offset = (int16_t)read_im16(env, s);
+    l1 = gen_new_label();
+    gen_jmpcc(s, (insn >> 8) & 0xf, l1);
+
+    tmp = tcg_temp_new();
+    tcg_gen_ext16s_i32(tmp, reg);
+    tcg_gen_addi_i32(tmp, tmp, -1);
+    gen_partset_reg(OS_WORD, reg, tmp);
+    tcg_gen_brcondi_i32(TCG_COND_EQ, tmp, -1, l1);
+    gen_jmp_tb(s, 1, base + offset);
+    gen_set_label(l1);
+    gen_jmp_tb(s, 0, s->pc);
+}
+
 DISAS_INSN(undef_mac)
 {
     gen_exception(s, s->pc - 2, EXCP_LINEA);
@@ -3144,7 +3167,9 @@ void register_m68k_insns (CPUM68KState *env)
     INSN(jump,      4ec0, ffc0, M68000);
     INSN(addsubq,   5000, f080, M68000);
     INSN(addsubq,   5080, f0c0, M68000);
-    INSN(scc,       50c0, f0f8, CF_ISA_A);
+    INSN(scc,       50c0, f0f8, CF_ISA_A); /* Scc.B Dx   */
+    INSN(scc,       50c0, f0c0, M68000);   /* Scc.B <EA> */
+    INSN(dbcc,      50c8, f0f8, M68000);
     INSN(addsubq,   5080, f1c0, CF_ISA_A);
     INSN(tpf,       51f8, fff8, CF_ISA_A);