py/viper: Allow casting of Python integers to viper pointers.

dpgeorge · dpgeorge · commit 3e02b1d19a4b · 2016-02-09T13:29:20.000Z
This allows you to pass a number (being an address) to a viper function
that expects a pointer, and also allows casting of integers to pointers
within viper functions.

This was actually the original behaviour, but it regressed due to native
type identifiers being promoted to 4 bits in width.
diff --git a/py/nativeglue.c b/py/nativeglue.c
@@ -50,10 +50,14 @@ mp_uint_t mp_convert_obj_to_native(mp_obj_t obj, mp_uint_t type) {
         case MP_NATIVE_TYPE_BOOL:
         case MP_NATIVE_TYPE_INT:
         case MP_NATIVE_TYPE_UINT: return mp_obj_get_int_truncated(obj);
-        default: { // a pointer
+        default: { // cast obj to a pointer
             mp_buffer_info_t bufinfo;
-            mp_get_buffer_raise(obj, &bufinfo, MP_BUFFER_RW);
-            return (mp_uint_t)bufinfo.buf;
+            if (mp_get_buffer(obj, &bufinfo, MP_BUFFER_RW)) {
+                return (mp_uint_t)bufinfo.buf;
+            } else {
+                // assume obj is an integer that represents an address
+                return mp_obj_get_int_truncated(obj);
+            }
         }
     }
 }
diff --git a/tests/micropython/viper_addr.py b/tests/micropython/viper_addr.py
@@ -0,0 +1,29 @@
+# test passing addresses to viper
+
+@micropython.viper
+def get_addr(x:ptr) -> ptr:
+    return x
+
+@micropython.viper
+def memset(dest:ptr8, c:int, n:int):
+    for i in range(n):
+        dest[i] = c
+
+# create array and get its address
+ar = bytearray('0000')
+addr = get_addr(ar)
+print(type(ar))
+print(type(addr))
+print(ar)
+
+# pass array as an object
+memset(ar, ord('1'), len(ar))
+print(ar)
+
+# pass direct pointer to array buffer
+memset(addr, ord('2'), len(ar))
+print(ar)
+
+# pass direct pointer to array buffer, with offset
+memset(addr + 2, ord('3'), len(ar) - 2)
+print(ar)
diff --git a/tests/micropython/viper_addr.py.exp b/tests/micropython/viper_addr.py.exp
@@ -0,0 +1,6 @@
+<class 'bytearray'>
+<class 'int'>
+bytearray(b'0000')
+bytearray(b'1111')
+bytearray(b'2222')
+bytearray(b'2233')

Original file line number	Diff line number	Diff line change
`@@ -50,10 +50,14 @@ mp_uint_t mp_convert_obj_to_native(mp_obj_t obj, mp_uint_t type) {`
`50`	`50`	`case MP_NATIVE_TYPE_BOOL:`
`51`	`51`	`case MP_NATIVE_TYPE_INT:`
`52`	`52`	`case MP_NATIVE_TYPE_UINT: return mp_obj_get_int_truncated(obj);`
`53`		`- default: { // a pointer`
	`53`	`+ default: { // cast obj to a pointer`
`54`	`54`	`mp_buffer_info_t bufinfo;`
`55`		`- mp_get_buffer_raise(obj, &bufinfo, MP_BUFFER_RW);`
`56`		`- return (mp_uint_t)bufinfo.buf;`
	`55`	`+ if (mp_get_buffer(obj, &bufinfo, MP_BUFFER_RW)) {`
	`56`	`+ return (mp_uint_t)bufinfo.buf;`
	`57`	`+ } else {`
	`58`	`+ // assume obj is an integer that represents an address`
	`59`	`+ return mp_obj_get_int_truncated(obj);`
	`60`	`+ }`
`57`	`61`	`}`
`58`	`62`	`}`
`59`	`63`	`}`