[app][tests][float] generally spiff up the test

Still doesn't seem to work right on some arches, will need
to debug whats going on.

app/tests/float.c

@@ -8,6 +8,7 @@
 #if ARM_WITH_VFP || ARCH_ARM64 || X86_WITH_FPU || (ARCH_RISCV && RISCV_FPU)
 
 #include <stdio.h>
+#include <inttypes.h>
 #include <rand.h>
 #include <lk/err.h>
 #include <lk/console_cmd.h>
@@ -23,30 +24,29 @@ extern void float_vfp_thumb_instruction_test(void);
 extern void float_neon_arm_instruction_test(void);
 extern void float_neon_thumb_instruction_test(void);
 
-#if !ARM_WITH_VFP_SP_ONLY
+#if ARM_WITH_VFP_SP_ONLY
 #define FLOAT float
 #else
-#define FLOAT float
+#define FLOAT double
 #endif
 
 /* optimize this function to cause it to try to use a lot of registers */
 __OPTIMIZE("O3")
 static int float_thread(void *arg) {
     FLOAT *val = arg;
-    uint i, j;
 
     FLOAT a[16];
 
     /* do a bunch of work with floating point to test context switching */
     a[0] = *val;
-    for (i = 1; i < countof(a); i++) {
-        a[i] = a[i-1] * 1.01f;
+    for (size_t i = 1; i < countof(a); i++) {
+        a[i] = a[i-1] * (FLOAT)1.01f;
     }
 
-    for (i = 0; i < 1000000; i++) {
-        a[0] += 0.001f;
-        for (j = 1; j < countof(a); j++) {
-            a[j] += a[j-1] * 0.00001f;
+    for (size_t i = 0; i < 1000000; i++) {
+        a[0] += (FLOAT)0.001f;
+        for (size_t j = 1; j < countof(a); j++) {
+            a[j] += a[j-1] * (FLOAT)0.00001f;
         }
     }
 
@@ -75,23 +75,25 @@ static int float_tests(int argc, const console_cmd_args *argv) {
 
     /* test lazy fpu load on separate thread */
     thread_t *t[8];
-    FLOAT val[countof(t)];
+    volatile FLOAT val[countof(t)];
 
     printf("creating %zu floating point threads\n", countof(t));
     for (uint i = 0; i < countof(t); i++) {
         val[i] = i;
         char name[32];
         snprintf(name, sizeof(name), "float %u", i);
-        t[i] = thread_create(name, &float_thread, &val[i], LOW_PRIORITY, DEFAULT_STACK_SIZE);
+        t[i] = thread_create(name, &float_thread, (void *)&val[i], LOW_PRIORITY, DEFAULT_STACK_SIZE);
         thread_resume(t[i]);
     }
 
     int res;
     for (uint i = 0; i < countof(t); i++) {
         thread_join(t[i], &res, INFINITE_TIME);
-        printf("float thread %u returns %d, val %f\n", i, res, (double)val[i]);
+        double result = (double)val[i];
+        printf("float thread %u returns %d, hex val %a\n", i, res, result);
+        //hexdump8(&result, 8);
     }
-    printf("the above values should be close\n");
+    printf("the above values should be valid and generally increasing, but close\n");
 
 #if ARCH_ARM && !ARM_ISA_ARMV7M
     /* test all the instruction traps */