py/inlineasm: Add ability to specify return type of asm_thumb funcs.

Supported return types are: object, bool, int, uint.

For example:

@micropython.asm_thumb
def foo(r0, r1) -> uint:
    add(r0, r0, r1)

2 files changed, 25 insertions, 0 deletions

diff --git a/tests/inlineasm/asmrettype.py b/tests/inlineasm/asmrettype.py
new file mode 100644
index 000000000..f1918696e
--- /dev/null
+++ b/tests/inlineasm/asmrettype.py
@@ -0,0 +1,21 @@
+# test return type of inline asm
+
+@micropython.asm_thumb
+def ret_obj(r0) -> object:
+    pass
+ret_obj(print)(1)
+
+@micropython.asm_thumb
+def ret_bool(r0) -> bool:
+    pass
+print(ret_bool(0), ret_bool(1))
+
+@micropython.asm_thumb
+def ret_int(r0) -> int:
+    lsl(r0, r0, 29)
+print(ret_int(0), hex(ret_int(1)), hex(ret_int(2)), hex(ret_int(4)))
+
+@micropython.asm_thumb
+def ret_uint(r0) -> uint:
+    lsl(r0, r0, 29)
+print(ret_uint(0), hex(ret_uint(1)), hex(ret_uint(2)), hex(ret_uint(4)))
diff --git a/tests/inlineasm/asmrettype.py.exp b/tests/inlineasm/asmrettype.py.exp
new file mode 100644
index 000000000..cbb49d247
--- /dev/null
+++ b/tests/inlineasm/asmrettype.py.exp
@@ -0,0 +1,4 @@
+1
+False True
+0 0x20000000 0x40000000 -0x80000000
+0 0x20000000 0x40000000 0x80000000