implement va_list for ARMv7 - cu_va_start and cu_va_arg works now based on frame-pointer (r11) for variable arguments, indexed differently than x86 stack ABI does

arch/ARMv7.S

@@ -182,7 +182,14 @@ cu_memtest:
     bx lr
 
 cu_va_start:
+    add r1, r11, #8
+    str r1, [r0]
     bx lr
 
 cu_va_arg:
+    // r0 - va_list, r1 - index
+    mov r1, r1, lsl #2
+    ldr r0, [r0]
+    add r0, r0, r1
+    ldr r0, [r0]
     bx lr

string.c

@@ -273,8 +273,11 @@ void cu_sprintf(char* dst, size_t maxLen, const char* fmt, ...)
     uword idx;
     char* cur,*end,c;
     char numbuf[64];
-    
+#ifdef CU_ARCH_ARM
+    idx = 0;
+#else
     idx = 3;
+#endif
     cur = dst;
     end = dst+maxLen;
     while((c = *fmt++) && cur != end)
@@ -360,8 +363,11 @@ void cu_sscanf(char* buf, char* fmt, ...)
         char* sptr;
     } u;
     char c,*stk;
-    
+#ifdef CU_ARCH_ARM
+    idx = 0;
+#else
     idx = 2;
+#endif
     while((c = *fmt))
     {
         //kprintf("%c %c\n",c,*buf);

test.c

@@ -177,7 +177,7 @@ int main()
     printf("cu_memset\tc0\t%p\n", cu_memtest(&c0, 1));
 
     printf("[va_list]\n");
-    //va_test(1337, 1, 2, 3, 4, 5);
+    va_test(1337, 1, 2, 3, 4, 5);
 
     printf("[string]\n");
     printf("cu_memcmp\t%u\n", cu_memcmp(val3, val3, sizeof(val3)));
@@ -188,7 +188,7 @@ int main()
     printf("cu_strcpy\tstr2\t\"%s\"\n", str2);
     printf("cu_strcmp\t%u\n", cu_strcmp(str2, str1));
 
-    /*char str3[64] = {0};
+    char str3[64] = {0};
     cu_sprintf(str3, 64, "hello %u world \"%s\"", 2312, "test");
     printf("cu_sprintf\t%s\n", str3);
 
@@ -196,7 +196,7 @@ int main()
     char str5[8] = {0};
     iword val5 = 0;
     cu_sscanf((char*)str4, "\"%s\" %d", str5, 8, &val5);
-    printf("cu_sscanf\t%s\t%u\n", str5, val5);*/
+    printf("cu_sscanf\t%s\t%u\n", str5, val5);
 
     printf("[heap]\n");
     static u8 heap_data[4096];

va_list.h

@@ -13,9 +13,15 @@
 #   define VA_NUM   0
 #endif
 
+#ifdef CU_ARCH_X86
 typedef struct {
     uword args[VA_NUM];
 } cu_va_list;
+#elif (defined(CU_ARCH_ARM))
+typedef struct {
+    uword fp;
+} cu_va_list;
+#endif
 
 extern void cu_va_start(cu_va_list* va);
 extern uword cu_va_arg(cu_va_list* va, unsigned idx);