target/m68k: add the Interrupt Stack Pointer

Add the third stack pointer, the Interrupt Stack Pointer (ISP)
(680x0 only). This stack will be needed in softmmu mode.

Update movec to set/get the value of the three stacks.

Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20180104012913.30763-17-laurent@vivier.eu>

1 files changed, 75 insertions, 7 deletions

diff --git a/target/m68k/helper.c b/target/m68k/helper.c
index 52b054e1a3..a999389e9a 100644
--- a/target/m68k/helper.c
+++ b/target/m68k/helper.c
@@ -171,28 +171,84 @@ void m68k_cpu_init_gdb(M68kCPU *cpu)
     /* TODO: Add [E]MAC registers.  */
 }
 
-void HELPER(movec)(CPUM68KState *env, uint32_t reg, uint32_t val)
+void HELPER(cf_movec_to)(CPUM68KState *env, uint32_t reg, uint32_t val)
 {
     M68kCPU *cpu = m68k_env_get_cpu(env);
 
     switch (reg) {
-    case 0x02: /* CACR */
+    case M68K_CR_CACR:
         env->cacr = val;
         m68k_switch_sp(env);
         break;
-    case 0x04: case 0x05: case 0x06: case 0x07: /* ACR[0-3] */
+    case M68K_CR_ACR0:
+    case M68K_CR_ACR1:
+    case M68K_CR_ACR2:
+    case M68K_CR_ACR3:
         /* TODO: Implement Access Control Registers.  */
         break;
-    case 0x801: /* VBR */
+    case M68K_CR_VBR:
         env->vbr = val;
         break;
     /* TODO: Implement control registers.  */
     default:
-        cpu_abort(CPU(cpu), "Unimplemented control register write 0x%x = 0x%x\n",
+        cpu_abort(CPU(cpu),
+                  "Unimplemented control register write 0x%x = 0x%x\n",
                   reg, val);
     }
 }
 
+void HELPER(m68k_movec_to)(CPUM68KState *env, uint32_t reg, uint32_t val)
+{
+    M68kCPU *cpu = m68k_env_get_cpu(env);
+
+    switch (reg) {
+    /* MC680[1234]0 */
+    case M68K_CR_VBR:
+        env->vbr = val;
+        return;
+    /* MC680[234]0 */
+    case M68K_CR_CACR:
+        env->cacr = val;
+        m68k_switch_sp(env);
+        return;
+    /* MC680[34]0 */
+    case M68K_CR_USP:
+        env->sp[M68K_USP] = val;
+        return;
+    case M68K_CR_MSP:
+        env->sp[M68K_SSP] = val;
+        return;
+    case M68K_CR_ISP:
+        env->sp[M68K_ISP] = val;
+        return;
+    }
+    cpu_abort(CPU(cpu), "Unimplemented control register write 0x%x = 0x%x\n",
+              reg, val);
+}
+
+uint32_t HELPER(m68k_movec_from)(CPUM68KState *env, uint32_t reg)
+{
+    M68kCPU *cpu = m68k_env_get_cpu(env);
+
+    switch (reg) {
+    /* MC680[1234]0 */
+    case M68K_CR_VBR:
+        return env->vbr;
+    /* MC680[234]0 */
+    case M68K_CR_CACR:
+        return env->cacr;
+    /* MC680[34]0 */
+    case M68K_CR_USP:
+        return env->sp[M68K_USP];
+    case M68K_CR_MSP:
+        return env->sp[M68K_SSP];
+    case M68K_CR_ISP:
+        return env->sp[M68K_ISP];
+    }
+    cpu_abort(CPU(cpu), "Unimplemented control register read 0x%x\n",
+              reg);
+}
+
 void HELPER(set_macsr)(CPUM68KState *env, uint32_t val)
 {
     uint32_t acc;
@@ -232,8 +288,20 @@ void m68k_switch_sp(CPUM68KState *env)
     int new_sp;
 
     env->sp[env->current_sp] = env->aregs[7];
-    new_sp = (env->sr & SR_S && env->cacr & M68K_CACR_EUSP)
-             ? M68K_SSP : M68K_USP;
+    if (m68k_feature(env, M68K_FEATURE_M68000)) {
+        if (env->sr & SR_S) {
+            if (env->sr & SR_M) {
+                new_sp = M68K_SSP;
+            } else {
+                new_sp = M68K_ISP;
+            }
+        } else {
+            new_sp = M68K_USP;
+        }
+    } else {
+        new_sp = (env->sr & SR_S && env->cacr & M68K_CACR_EUSP)
+                 ? M68K_SSP : M68K_USP;
+    }
     env->aregs[7] = env->sp[new_sp];
     env->current_sp = new_sp;
 }