target-m68k: initialize FPU registers

on reset, set FP registers to NaN and control registers to 0

Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Message-Id: <20170620205121.26515-3-laurent@vivier.eu>

target/m68k/cpu.c

@@ -49,6 +49,8 @@ static void m68k_cpu_reset(CPUState *s)
     M68kCPU *cpu = M68K_CPU(s);
     M68kCPUClass *mcc = M68K_CPU_GET_CLASS(cpu);
     CPUM68KState *env = &cpu->env;
+    float64 nan = float64_default_nan(NULL);
+    int i;
 
     mcc->parent_reset(s);
 
@@ -57,7 +59,12 @@ static void m68k_cpu_reset(CPUState *s)
     env->sr = 0x2700;
 #endif
     m68k_switch_sp(env);
-    /* ??? FP regs should be initialized to NaN.  */
+    for (i = 0; i < 8; i++) {
+        env->fregs[i] = nan;
+    }
+    env->fpcr = 0;
+    env->fpsr = 0;
+
     cpu_m68k_set_ccr(env, 0);
     /* TODO: We should set PC from the interrupt vector.  */
     env->pc = 0;