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

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
 

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)

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);