From 6a5b1b362ecf78ce2925068a5d938d319ff583a3 Mon Sep 17 00:00:00 2001
From: notaz <notasas@gmail.com>
Date: Fri, 18 Aug 2017 03:44:25 +0300
Subject: [PATCH] sh2: handle some branch exceptions

---
 cpu/sh2/compiler.c     | 31 +++++++++++++++++++++++++++----
 cpu/sh2/compiler.h     |  1 +
 cpu/sh2/mame/sh2pico.c | 12 ++++++++++++
 3 files changed, 40 insertions(+), 4 deletions(-)

diff --git a/cpu/sh2/compiler.c b/cpu/sh2/compiler.c
index 25ba9d2f..3a2b708c 100644
--- a/cpu/sh2/compiler.c
+++ b/cpu/sh2/compiler.c
@@ -2590,8 +2590,9 @@ static void REGPARM(2) *sh2_translate(SH2 *sh2, int tcache_id)
 
     default:
     default_:
-      elprintf_sh2(sh2, EL_ANOMALY,
-        "drc: illegal op %04x @ %08x", op, pc - 2);
+      if (!(op_flags[i] & OF_B_IN_DS))
+        elprintf_sh2(sh2, EL_ANOMALY,
+          "drc: illegal op %04x @ %08x", op, pc - 2);
 
       tmp = rcache_get_reg(SHR_SP, RC_GR_RMW);
       emith_sub_r_imm(tmp, 4*2);
@@ -2604,10 +2605,16 @@ static void REGPARM(2) *sh2_translate(SH2 *sh2, int tcache_id)
       // push PC
       rcache_get_reg_arg(0, SHR_SP);
       tmp = rcache_get_tmp_arg(1);
-      emith_move_r_imm(tmp, pc - 2);
+      if (drcf.pending_branch_indirect) {
+        tmp2 = rcache_get_reg(SHR_PC, RC_GR_READ);
+        emith_move_r_r(tmp, tmp2);
+      }
+      else
+        emith_move_r_imm(tmp, pc - 2);
       emit_memhandler_write(2);
       // obtain new PC
-      emit_memhandler_read_rr(SHR_PC, SHR_VBR, 4 * 4, 2);
+      v = (op_flags[i] & OF_B_IN_DS) ? 6 : 4;
+      emit_memhandler_read_rr(SHR_PC, SHR_VBR, v * 4, 2);
       // indirect jump -> back to dispatcher
       rcache_flush();
       emith_jump(sh2_drc_dispatcher);
@@ -4062,6 +4069,22 @@ void scan_block(u32 base_pc, int is_slave, u8 *op_flags, u32 *end_pc_out,
         is_slave ? 's' : 'm', op, pc);
       break;
     }
+
+    if (op_flags[i] & OF_DELAY_OP) {
+      switch (opd->op) {
+      case OP_BRANCH:
+      case OP_BRANCH_CT:
+      case OP_BRANCH_CF:
+      case OP_BRANCH_R:
+      case OP_BRANCH_RF:
+        elprintf(EL_ANOMALY, "%csh2 drc: branch in DS @ %08x",
+          is_slave ? 's' : 'm', pc);
+        opd->op = OP_UNHANDLED;
+        op_flags[i] |= OF_B_IN_DS;
+        next_is_delay = 0;
+        break;
+      }
+    }
   }
   i_end = i;
   end_pc = pc;
diff --git a/cpu/sh2/compiler.h b/cpu/sh2/compiler.h
index ef1944b4..61d8d2da 100644
--- a/cpu/sh2/compiler.h
+++ b/cpu/sh2/compiler.h
@@ -20,6 +20,7 @@ void sh2_drc_frame(void);
 #define OF_BTARGET    (1 << 1)
 #define OF_T_SET      (1 << 2) // T is known to be set
 #define OF_T_CLEAR    (1 << 3) // ... clear
+#define OF_B_IN_DS    (1 << 4)
 
 void scan_block(unsigned int base_pc, int is_slave,
 		unsigned char *op_flags, unsigned int *end_pc,
diff --git a/cpu/sh2/mame/sh2pico.c b/cpu/sh2/mame/sh2pico.c
index a3ad9f47..174d4691 100644
--- a/cpu/sh2/mame/sh2pico.c
+++ b/cpu/sh2/mame/sh2pico.c
@@ -122,6 +122,18 @@ int sh2_execute_interpreter(SH2 *sh2, int cycles)
 		{
 			sh2->ppc = sh2->delay;
 			opcode = RW(sh2, sh2->delay);
+
+			// TODO: more branch types
+			if ((opcode >> 13) == 5) { // BRA/BSR
+				sh2->r[15] -= 4;
+				WL(sh2, sh2->r[15], sh2->sr);
+				sh2->r[15] -= 4;
+				WL(sh2, sh2->r[15], sh2->pc);
+				sh2->pc = RL(sh2, sh2->vbr + 6 * 4);
+				sh2->icount -= 5;
+				opcode = 9; // NOP
+			}
+
 			sh2->pc -= 2;
 		}
 		else
-- 
2.39.5