cbm_write() added

changed/added some comments
all cbm_* IO functions are using _oserror now


git-svn-id: svn://svn.cc65.org/cc65/trunk@682 b7a2c559-68d2-44c3-8de9-860c34a00d81

libsrc/cbm/cbm_write.c

@@ -0,0 +1,32 @@
+/*
+ * Marc 'BlackJack' Rintsch, 25.03.2001
+ *
+ * int cbm_write(unsigned char lfn, void* buffer, unsigned int size);
+ */
+
+#include <cbm.h>
+
+extern unsigned char _oserror;
+
+int cbm_write(unsigned char lfn, void* buffer, unsigned int size) {
+
+    static unsigned int byteswritten;
+    
+    /* if we can't change to the outputchannel #lfn then return an error */
+    if (_oserror = cbm_k_ckout(lfn)) return -1;
+    
+    byteswritten = 0;
+    
+    while (byteswritten<size && !cbm_k_readst()) {
+        cbm_k_bsout(((unsigned char*)buffer)[byteswritten++]);
+    }
+
+    if (cbm_k_readst()) {
+        _oserror = 5; /* device not present */
+        byteswritten = -1;
+    }
+        
+    cbm_k_clrch();
+    
+    return byteswritten;
+}