m68k: implement movep instruction

This patch implements movep instruction. It moves data between a data register
and alternate bytes within the address space starting at the location
specified and incrementing by two.

It was designed for the original 68000 and used in firmwares for
interfacing the 8-bit peripherals through the 16-bit data bus.
Without this patch opcode for this instruction is recognized as some bitop.

Signed-off-by: Pavel Dovgalyuk <pavel.dovgaluk@ispras.ru>
Signed-off-by: Mihail Abakumov <mikhail.abakumov@ispras.ru>
Tested-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20180206124431.31433.91946.stgit@pasha-VirtualBox>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

3 files changed, 49 insertions, 0 deletions

diff --git a/target/m68k/cpu.c b/target/m68k/cpu.c
index 6a80be0..3026714 100644
--- a/target/m68k/cpu.c
+++ b/target/m68k/cpu.c
@@ -113,6 +113,7 @@ static void m68000_cpu_initfn(Object *obj)
     m68k_set_feature(env, M68K_FEATURE_M68000);
     m68k_set_feature(env, M68K_FEATURE_USP);
     m68k_set_feature(env, M68K_FEATURE_WORD_INDEX);
+    m68k_set_feature(env, M68K_FEATURE_MOVEP);
 }
 
 static void m68020_cpu_initfn(Object *obj)
@@ -135,6 +136,7 @@ static void m68020_cpu_initfn(Object *obj)
     m68k_set_feature(env, M68K_FEATURE_BKPT);
     m68k_set_feature(env, M68K_FEATURE_RTD);
     m68k_set_feature(env, M68K_FEATURE_CHK2);
+    m68k_set_feature(env, M68K_FEATURE_MOVEP);
 }
 #define m68030_cpu_initfn m68020_cpu_initfn
 
diff --git a/target/m68k/cpu.h b/target/m68k/cpu.h
index 627fb78..1d79885 100644
--- a/target/m68k/cpu.h
+++ b/target/m68k/cpu.h
@@ -492,6 +492,7 @@ enum m68k_features {
     M68K_FEATURE_RTD,
     M68K_FEATURE_CHK2,
     M68K_FEATURE_M68040, /* instructions specific to MC68040 */
+    M68K_FEATURE_MOVEP,
 };
 
 static inline int m68k_feature(CPUM68KState *env, int feature)
diff --git a/target/m68k/translate.c b/target/m68k/translate.c
index 34db97b..70c7583 100644
--- a/target/m68k/translate.c
+++ b/target/m68k/translate.c
@@ -2078,6 +2078,51 @@ DISAS_INSN(movem)
     tcg_temp_free(addr);
 }
 
+DISAS_INSN(movep)
+{
+    uint8_t i;
+    int16_t displ;
+    TCGv reg;
+    TCGv addr;
+    TCGv abuf;
+    TCGv dbuf;
+
+    displ = read_im16(env, s);
+
+    addr = AREG(insn, 0);
+    reg = DREG(insn, 9);
+
+    abuf = tcg_temp_new();
+    tcg_gen_addi_i32(abuf, addr, displ);
+    dbuf = tcg_temp_new();
+
+    if (insn & 0x40) {
+        i = 4;
+    } else {
+        i = 2;
+    }
+
+    if (insn & 0x80) {
+        for ( ; i > 0 ; i--) {
+            tcg_gen_shri_i32(dbuf, reg, (i - 1) * 8);
+            tcg_gen_qemu_st8(dbuf, abuf, IS_USER(s));
+            if (i > 1) {
+                tcg_gen_addi_i32(abuf, abuf, 2);
+            }
+        }
+    } else {
+        for ( ; i > 0 ; i--) {
+            tcg_gen_qemu_ld8u(dbuf, abuf, IS_USER(s));
+            tcg_gen_deposit_i32(reg, reg, dbuf, (i - 1) * 8, 8);
+            if (i > 1) {
+                tcg_gen_addi_i32(abuf, abuf, 2);
+            }
+        }
+    }
+    tcg_temp_free(abuf);
+    tcg_temp_free(dbuf);
+}
+
 DISAS_INSN(bitop_im)
 {
     int opsize;
@@ -5678,6 +5723,7 @@ void register_m68k_insns (CPUM68KState *env)
     BASE(bitop_reg, 0140, f1c0);
     BASE(bitop_reg, 0180, f1c0);
     BASE(bitop_reg, 01c0, f1c0);
+    INSN(movep,     0108, f138, MOVEP);
     INSN(arith_im,  0280, fff8, CF_ISA_A);
     INSN(arith_im,  0200, ff00, M68000);
     INSN(undef,     02c0, ffc0, M68000);