4 files changed, 25 insertions, 14 deletions

diff --git a/src/common.h b/src/common.h
index c71455d..39b2c91 100644
--- a/src/common.h
+++ b/src/common.h
@@ -25,6 +25,14 @@ void delay(u64 ticks);
 // Clear N bytes at the given address 8 bytes at a time. Implemented in start.s.
 void memzero64(void *src, u64 n);
 
+static void
+memzero8(void *src, u64 n) {
+    u8 * ptr = src;
+    for (size_t i = 0; i < n; i++) {
+        ptr[i] = 0;
+    }
+}
+
 //
 // GPIO Registers.
 //
@@ -249,7 +257,7 @@ typedef struct TimerRegs {
 
 #define TIMER ((TimerRegs *)(MEM_BASE + 0x00003000))
 
-u64
+static u64
 timer_get_ticks(void) {
     u32 high = TIMER->counter_high;
     u32 low = TIMER->counter_low;
@@ -263,7 +271,7 @@ timer_get_ticks(void) {
     return ((u64)high << 32) | low;
 }
 
-void
+static void
 wait(u64 usec) {
     u64 current_ticks = timer_get_ticks();
     // The system timer clock runs at 1 Mhz.
@@ -274,7 +282,7 @@ wait(u64 usec) {
 // Utilities.
 //
 
-void *
+static void *
 memcpy(void *dest, const void *src, u32 n) {
     u8 *from = (u8*)src;
     u8 *to = (u8*)dest;
diff --git a/src/main.c b/src/main.c
index 8ab3cf5..b18b129 100644
--- a/src/main.c
+++ b/src/main.c
@@ -129,10 +129,7 @@ init_uxn() {
     uart_puts("Initializing UXN.\n");
 
     // Clear UXN memory.
-    u8 * uxnptr = (u8*)&u;
-    for (size_t i = 0; i < sizeof(Uxn); i++) {
-        uxnptr[i] = 0;
-    }
+    memzero8(&u, sizeof(Uxn));
 
     ppu_init(&ppu, SCREEN_WIDTH / 8,  SCREEN_HEIGHT / 8);
 
@@ -164,10 +161,13 @@ void
 clear_bss(void) {
     extern u64 __bss_start;
     extern u64 __bss_end;
-    memzero64(&__bss_start, &__bss_end - &__bss_start);
+    u64 bss_size = &__bss_end - &__bss_start;
+    memzero64(&__bss_start, bss_size);
 }
 
-void main(void) {
+void
+main(void) {
+    // Initialization.
     clear_bss();
     uart_init();
     init_uxn();
diff --git a/src/ppu.c b/src/ppu.c
index ac0feeb..50e95d5 100644
--- a/src/ppu.c
+++ b/src/ppu.c
@@ -151,9 +151,7 @@ ppu_init(Ppu *p, Uint8 hor, Uint8 ver) {
     palette[3] = 0xff7777;
 
     // Clear pixel buffer memory.
-    for (size_t i = 0; i < sizeof(pixels_buf); i++) {
-        p->pixels[i] = 0;
-    }
+    memzero8(pixels_buf, sizeof(pixels_buf));
 
     // Make sure we perform an initial screen drawing.
     reqdraw = 1;
diff --git a/src/start.s b/src/start.s
index b6a6d0f..8f8ca2f 100644
--- a/src/start.s
+++ b/src/start.s
@@ -11,9 +11,14 @@ _start:
 // Helper function to clear x1 bytes starting at the x0 memory address.
 .globl memzero64
 memzero64:
+    mov     x2, x1
+    lsr     x2, x2, #3
+    cbz     x2, memzero64_ret
+memzero64_loop:
         str     xzr, [x0], #8
-        subs    x1, x1, #8
-        b.gt    memzero64
+        subs    x2, x2, #1
+        b.gt    memzero64_loop
+memzero64_ret:
         ret
 
 // Helper function wait for N cycles before returning.