dead simple printf/sprintf implementation.

[lunaix-os.git] / lunaix-os / libs / libc / stdio / sprintf.c

diff --git a/lunaix-os/libs/libc/stdio/sprintf.c b/lunaix-os/libs/libc/stdio/sprintf.c
new file mode 100644 (file)
index 0000000..15a7fe2
--- /dev/null
+++ b/lunaix-os/libs/libc/stdio/sprintf.c
@@ -0,0 +1,93 @@
+#define __LUNAIX_LIBC
+#include <libc/stdio.h>
+#include <libc/stdlib.h>
+#include <libc/string.h>
+#include <stdint.h>
+
+void
+__sprintf_internal(char* buffer, char* fmt, va_list args)
+{
+    char c;
+    int num;
+    unsigned int ptr = 0;
+    unsigned int adv = 0;
+    while ((c = *fmt)) {
+        if (c != '%') {
+            buffer[ptr] = c;
+            adv = 1;
+        } else {
+            adv = 0;
+            fmt++;
+            switch (c = *fmt) {
+                case 'c': {
+                    buffer[ptr] = (char)va_arg(args, int);
+                    adv = 1;
+                    break;
+                }
+                case 's': {
+                    char* str = va_arg(args, char*);
+                    strcpy(buffer + ptr, str);
+                    adv = strlen(str);
+                    break;
+                }
+                case 'i':
+                // fall through
+                case 'd': {
+                    num = va_arg(args, int);
+                    __itoa_internal(num, buffer + ptr, 10, &adv);
+                    break;
+                }
+                case 'u': {
+                    unsigned int unum = va_arg(args, unsigned int);
+                    __uitoa_internal(unum, buffer + ptr, 10, &adv);
+                    break;
+                }
+                case 'o': {
+                    num = va_arg(args, int);
+                    __itoa_internal(num, buffer + ptr, 8, &adv);
+                    break;
+                }
+                case 'x':
+                // fall through
+                case 'X': {
+                    num = va_arg(args, int);
+                    __itoa_internal(num, buffer + ptr, 16, &adv);
+                    if (c == 'X') {
+                        int p = ptr;
+                        char c_;
+                        while ((c_ = buffer[p])) {
+                            buffer[p] = c_ & ~((c_ & 0x40) >> 1);
+                            p++;
+                        }
+                    }
+                    break;
+                }
+                case 'p': {
+                    uintptr_t dptr = va_arg(args, uintptr_t);
+                    __itoa_internal((int)dptr, buffer + ptr, 16, &adv);
+                    break;
+                }
+                case '%': {
+                    buffer[ptr] = c;
+                    adv = 1;
+                    break;
+                }
+                default:
+                    // unknown
+                    break;
+            }
+        }
+        fmt++;
+        ptr += adv;
+    }
+    buffer[ptr] = '\0';
+}
+
+void
+sprintf(char* buffer, char* fmt, ...)
+{
+    va_list args;
+    va_start(args, fmt);
+    __sprintf_internal(buffer, fmt, args);
+    va_end(args);
+}
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