Add UVM32_SYSCALL_RAND to get a "true" random number from the host, as I want to play zigtris and not have it be the same every time.

apps/common/uvm32_target.h

@@ -50,6 +50,7 @@ static uint32_t syscall(uint32_t id, uint32_t param1, uint32_t param2) {
 #define printbuf(x, y)  syscall_cast(UVM32_SYSCALL_PRINTBUF, x, y)
 #define render(x, y)    syscall_cast(UVM32_SYSCALL_RENDER, x, y)
 #define getkey()        syscall_cast(UVM32_SYSCALL_GETKEY, 0, 0)
+#define rand()          syscall_cast(UVM32_SYSCALL_RAND, 0, 0)
 
 extern char _estack;
 

apps/zigtris/src/main.zig

@@ -10,7 +10,7 @@ export fn main() void {
     var gameRunning = true;
     var lastUpdate:u32 = 0;
 
-    zigtris.gamesetup(console, uvm.millis()) catch |err| {
+    zigtris.gamesetup(console, uvm.rand()) catch |err| {
         _ = console.print("err {any}\n", .{err}) catch 0;
         _ = console.flush() catch 0;
         return;

apps/zigtris/src/uvm.zig

@@ -27,6 +27,10 @@ pub inline fn millis() u32 {
     return syscall(uvm32.UVM32_SYSCALL_MILLIS, 0, 0);
 }
 
+pub inline fn rand() u32 {
+    return syscall(uvm32.UVM32_SYSCALL_RAND, 0, 0);
+}
+
 // dupeZ would be better, but want to avoid using an allocator
 // this is of course, unsafe...
 var termination_buf:[128]u8 = undefined;

common/uvm32_common_custom.h

@@ -14,4 +14,6 @@
 #define UVM32_SYSCALL_GETKEY      0x00000009
 #define UVM32_SYSCALL_RENDERAUDIO 0x0000000A
 #define UVM32_SYSCALL_CANRENDERAUDIO 0x0000000B
+#define UVM32_SYSCALL_RAND        0x0000000C
+
 

hosts/host-sdl/host-sdl.c

@@ -241,6 +241,8 @@ int main(int argc, char *argv[]) {
         return 1;
     }
 
+    srand(clock());
+
     uvm32_init(vmst);
 
     if (!uvm32_load(vmst, rom, romlen)) {
@@ -374,6 +376,9 @@ int main(int argc, char *argv[]) {
                     case UVM32_SYSCALL_MILLIS: {
                         uvm32_arg_setval(vmst, &evt, RET, SDL_GetTicks());
                     } break;
+                    case UVM32_SYSCALL_RAND:
+                        uvm32_arg_setval(&vmst, &evt, RET, rand());
+                    break;
                     case UVM32_SYSCALL_GETC: {
                         uvm32_arg_setval(vmst, &evt, RET, 0xFFFFFFFF);
                     } break;

hosts/host/host.c

@@ -190,6 +190,8 @@ int main(int argc, char *argv[]) {
         return 1;
     }
 
+    srand(clock());
+
     uvm32_init(&vmst);
 
     if (!uvm32_load(&vmst, rom, romlen)) {
@@ -264,6 +266,9 @@ int main(int argc, char *argv[]) {
                     case UVM32_SYSCALL_PRINTHEX:
                         printf("%08x", uvm32_arg_getval(&vmst, &evt, ARG0));
                     break;
+                    case UVM32_SYSCALL_RAND:
+                        uvm32_arg_setval(&vmst, &evt, RET, rand());
+                    break;
                     case UVM32_SYSCALL_MILLIS: {
                         clock_t now = clock() / (CLOCKS_PER_SEC / 1000);
                         uvm32_arg_setval(&vmst, &evt, RET, now - start_time);