From 9ef784dcc6aa2abd7325b43f3d1613b8ac5d9f3f Mon Sep 17 00:00:00 2001
From: Damien George <damien.p.george@gmail.com>
Date: Wed, 1 May 2019 15:24:21 +1000
Subject: [PATCH] py/asmthumb: Support asm_thumb code running on normal ARM
processors.
With this change, @micropython.asm_thumb functions will work on standard
ARM processors (that are in ARM state by default), in scripts and
precompiled .mpy files.
Addresses issue #4675.
---
py/asmthumb.c | 17 +++++++++++++++++
py/compile.c | 2 +-
2 files changed, 18 insertions(+), 1 deletion(-)
diff --git a/py/asmthumb.c b/py/asmthumb.c
index e6bba7ea6..68fb8f29e 100644
--- a/py/asmthumb.c
+++ b/py/asmthumb.c
@@ -33,6 +33,8 @@
// wrapper around everything in this file
#if MICROPY_EMIT_THUMB || MICROPY_EMIT_INLINE_THUMB
+#include "py/mpstate.h"
+#include "py/persistentcode.h"
#include "py/mphal.h"
#include "py/asmthumb.h"
@@ -118,6 +120,21 @@ STATIC void asm_thumb_write_word32(asm_thumb_t *as, int w32) {
void asm_thumb_entry(asm_thumb_t *as, int num_locals) {
assert(num_locals >= 0);
+ // If this Thumb machine code is run from ARM state then add a prelude
+ // to switch to Thumb state for the duration of the function.
+ #if MICROPY_DYNAMIC_COMPILER || MICROPY_EMIT_ARM || (defined(__arm__) && !defined(__thumb2__))
+ #if MICROPY_DYNAMIC_COMPILER
+ if (mp_dynamic_compiler.native_arch == MP_NATIVE_ARCH_ARMV6)
+ #endif
+ {
+ asm_thumb_op32(as, 0x4010, 0xe92d); // push {r4, lr}
+ asm_thumb_op32(as, 0xe009, 0xe28f); // add lr, pc, 8 + 1
+ asm_thumb_op32(as, 0xff3e, 0xe12f); // blx lr
+ asm_thumb_op32(as, 0x4010, 0xe8bd); // pop {r4, lr}
+ asm_thumb_op32(as, 0xff1e, 0xe12f); // bx lr
+ }
+ #endif
+
// work out what to push and how many extra spaces to reserve on stack
// so that we have enough for all locals and it's aligned an 8-byte boundary
// we push extra regs (r1, r2, r3) to help do the stack adjustment
diff --git a/py/compile.c b/py/compile.c
index 4919a1659..01e4ff9b6 100644
--- a/py/compile.c
+++ b/py/compile.c
@@ -124,7 +124,7 @@ STATIC const emit_inline_asm_method_table_t *emit_asm_table[] = {
NULL,
NULL,
NULL,
- NULL,
+ &emit_inline_thumb_method_table,
&emit_inline_thumb_method_table,
&emit_inline_thumb_method_table,
&emit_inline_thumb_method_table,
--
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