X-Git-Url: https://git.ucc.asn.au/?a=blobdiff_plain;f=ROM2%2Fhelpers.c;h=b66f5ee60dd8cad3f08c05cc9a30423b9c721e6f;hb=27fb8a023fa0572ef4171624781460bc59537d49;hp=0ef21cbd6db8459d35fa711bafe20429b5f0e5e2;hpb=84d9b234f38e34e5a72faed1badf2044191db18a;p=uccvend-snackrom.git

diff --git a/ROM2/helpers.c b/ROM2/helpers.c
index 0ef21cb..b66f5ee 100644
--- a/ROM2/helpers.c
+++ b/ROM2/helpers.c
@@ -1,21 +1,41 @@
-#include "display.h"
+#include "display_basic.h"
 #include "vend.h"
 
-#define DELAY_MAGIC 20 /* FIXME: number of loops for ~ 1 millisecond (< 256) */
 void delay(u16 ms) {
+	/* delay routine written in assembly so we know what we're really getting.
+	 * each inner loop should take ~1 ms to execute.
+	 * 15 cycles * (1/4.9152Mhz) * 327 = 0.997 ms + a little bit on the fringes.
+	 *
+	 * XXX - how do we know gcc isn't optimising this? it seems to optimise after
+	 * parsing C -> asm, but before asm -> machine code.
+	 */
+	asm volatile ("pshx\npsha\npshb\n"); /* save registers */
+	asm volatile ("ldx %0\n" :: "m" (ms));
+	asm volatile (
+		"loop:\n"
+		"	dex\n"                  /* 3 */
+		"	beq out\n"              /* 3 */
+		"	ldd #327\n"             /* 3 */
+		"inner_loop:\n" /* 15 cycles each */
+		"	cpd #0x0000\n"          /* 5 */
+		"	beq inner_loop_end\n"   /* 3 */
+		"	subd #0x0001\n"         /* 4 */
+		"	bra inner_loop\n"       /* 3 */
+		"inner_loop_end:\n"
+		"	bra loop\n"             /* 3 */
+		"out:\n"
+		"	pulb\n"
+		"	pula\n"
+		"	pulx\n");
+}
+
+void my_strncpy(char* dst, char* src, u8 max_size) {
 	u8 i;
-	for (;ms;ms--) {
-		for (i=0;i<DELAY_MAGIC; i++)
-			asm("nop\nnop\nnop\nnop\nnop\n");
-	}
+	for (i = 0; src[i] && i < max_size; i++) dst[i] = src[i];
+	if (src[i] == 0 && i < max_size) dst[i] = 0; /* null terminator */
 }
 
-void print_amount(u16 amt) {
-	/* take amt and show it on screen with a $ sign */
-	char str[10] = {' ', '$', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' '};
-	u8 pos;
-	for (pos = 7; amt; pos--, amt/=10) {
-		str[pos] = amt%10 + '0';
-	}
-	set_msg(str, WRAP_NONE);
+void my_memcpy(char* dst, char* src, u8 size) {
+	u8 i = 0;
+	for (i = 0; i < size; i++) dst[i] = src[i];
 }