[Qemu-devel] [PATCH 014/111] m68k: add DBcc instruction.

[Bryce Lanham <blanham@gmail.com>]

From: Laurent Vivier <laurent@vivier.eu>

Define DBcc instruction and attach it to M68000 feature.

Signed-off-by: Andreas Schwab <schwab@linux-m68k.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
---
 target-m68k/translate.c |   26 ++++++++++++++++++++++++++
 1 files changed, 26 insertions(+), 0 deletions(-)

diff --git a/target-m68k/translate.c b/target-m68k/translate.c
index 8cf49d8..e0edc6d 100644
--- a/target-m68k/translate.c
+++ b/target-m68k/translate.c
@@ -920,6 +920,31 @@ DISAS_INSN(scc_mem)
     tcg_temp_free(dest);
 }
 
+DISAS_INSN(dbcc)
+{
+    int l1;
+    TCGv reg;
+    TCGv tmp;
+    int16_t offset;
+    uint32_t base;
+
+    reg = DREG(insn, 0);
+    base = s->pc;
+    offset = ldsw_code(s->pc);
+    s->pc += 2;
+    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, 0, 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);
@@ -2991,6 +3016,7 @@ void register_m68k_insns (CPUM68KState *env)
     INSN(scc,       50c0, f0f8, CF_ISA_A);
     INSN(scc_mem,   50c0, f0c0, M68000);
     INSN(scc,       50c0, f0f8, M68000);
+    INSN(dbcc,      50c8, f0f8, M68000);
     INSN(tpf,       51f8, fff8, CF_ISA_A);
 
     /* Branch instructions.  */
-- 
1.7.2.3