py: Add NLR support for xtensa CPU.

py/nlr.h

@@ -47,6 +47,8 @@ struct _nlr_buf_t {
   #endif
 #elif defined(__thumb2__) || defined(__thumb__) || defined(__arm__)
     void *regs[10];
+#elif defined(__xtensa__)
+    void *regs[10];
 #else
     #define MICROPY_NLR_SETJMP (1)
     //#warning "No native NLR support for this arch, using setjmp implementation"

py/nlrxtensa.S

+/*
+ * This file is part of the Micro Python project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2014 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#if defined(__xtensa__)
+
+/*
+    calling conventions:
+    a0 = return address
+    a1 = stack pointer
+    a2 = first arg, return value
+    a3-a7 = rest of args
+*/
+
+    .file   "nlr.s"
+    .text
+
+    .literal_position
+    .literal .LC0, nlr_top
+    .align  4
+    .global nlr_push
+    .type   nlr_push, @function
+nlr_push:
+    // save regs
+    s32i.n  a0, a2, 8
+    s32i.n  a1, a2, 12
+    s32i.n  a8, a2, 16
+    s32i.n  a9, a2, 20
+    s32i.n  a10, a2, 24
+    s32i.n  a11, a2, 28
+    s32i.n  a12, a2, 32
+    s32i.n  a13, a2, 36
+    s32i.n  a14, a2, 40
+    s32i.n  a15, a2, 44
+
+    l32r    a3, .LC0
+    l32i.n  a4, a3, 0
+    s32i.n  a2, a3, 0
+    s32i.n  a4, a2, 0
+    movi.n  a2, 0
+    ret.n
+    .size   nlr_push, .-nlr_push
+
+    .literal_position
+    .literal .LC1, nlr_top
+    .align  4
+    .global nlr_pop
+    .type   nlr_pop, @function
+nlr_pop:
+    l32r    a2, .LC1
+    l32i.n  a3, a2, 0
+    l32i.n  a3, a3, 0
+    s32i.n  a3, a2, 0
+    ret.n
+    .size   nlr_pop, .-nlr_pop
+
+    .literal_position
+    .literal .LC2, nlr_top
+    .align    4
+    .global    nlr_jump
+    .type    nlr_jump, @function
+nlr_jump:
+    l32r    a3, .LC2
+    l32i.n  a3, a3, 0   // a3 = nlr_top
+    bnez.n  a3, .L4
+    call0   nlr_jump_fail
+.L4:
+    s32i.n  a2, a3, 4   // nlr_top->ret_val = val
+
+    // restore regs
+    l32i.n  a0, a3, 8
+    l32i.n  a1, a3, 12
+    l32i.n  a8, a3, 16
+    l32i.n  a9, a3, 20
+    l32i.n  a10, a3, 24
+    l32i.n  a11, a3, 28
+    l32i.n  a12, a3, 32
+    l32i.n  a13, a3, 36
+    l32i.n  a14, a3, 40
+    l32i.n  a15, a3, 44
+
+    l32i.n  a3, a3, 0   // a3 = nlr_top->prev
+    l32r    a2, .LC2
+    s32i.n  a3, a2, 0   // nlr_top = a3
+    movi.n  a2, 1       // return 1
+    ret.n
+    .size   nlr_jump, .-nlr_jump
+
+    .local  nlr_top
+    .comm   nlr_top,4,4
+
+#endif // defined(__xtensa__)

py/py.mk

@@ -15,6 +15,7 @@ PY_O_BASENAME = \
 	nlrx86.o \
 	nlrx64.o \
 	nlrthumb.o \
+	nlrxtensa.o \
 	nlrsetjmp.o \
 	malloc.o \
 	gc.o \