From 003e51b6925ca3cfe3b93a3fbc1ef632bc2e45e9 Mon Sep 17 00:00:00 2001
From: mykola2312 <49044616+mykola2312@users.noreply.github.com>
Date: Sat, 21 May 2022 10:38:35 +0300
Subject: [PATCH] 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 |  7 +++++++
 string.c     | 10 ++++++++--
 test.c       |  6 +++---
 va_list.h    |  6 ++++++
 4 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/arch/ARMv7.S b/arch/ARMv7.S
index ab05a60..0356054 100644
--- a/arch/ARMv7.S
+++ b/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
diff --git a/string.c b/string.c
index 7428c47..6a5cca7 100644
--- a/string.c
+++ b/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);
diff --git a/test.c b/test.c
index b17fc68..ea37957 100644
--- a/test.c
+++ b/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];
diff --git a/va_list.h b/va_list.h
index 1f5061e..4f37e89 100644
--- a/va_list.h
+++ b/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);