modmachine: Add new module to access hardware, starting with physical memory.

Refactored from "stm" module, provides mem8, mem16, mem32 objects with
array subscript syntax.

extmod/modmachine.c

+/*
+ * This file is part of the Micro Python project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2013, 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.
+ */
+
+#include <stdio.h>
+#include <stdint.h>
+
+#include "py/nlr.h"
+#include "py/obj.h"
+
+#if MICROPY_PY_MACHINE
+
+STATIC mp_uint_t get_read_addr(mp_obj_t addr_o, uint align) {
+    mp_uint_t addr = mp_obj_int_get_truncated(addr_o);
+    if ((addr & (align - 1)) != 0) {
+        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError, "address %08x is not aligned to %d bytes", addr, align));
+    }
+    return addr;
+}
+
+STATIC mp_uint_t get_write_addr(mp_obj_t addr_o, uint align) {
+    mp_uint_t addr = mp_obj_int_get_truncated(addr_o);
+    if ((addr & (align - 1)) != 0) {
+        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError, "address %08x is not aligned to %d bytes", addr, align));
+    }
+    return addr;
+}
+
+typedef struct _machine_mem_obj_t {
+    mp_obj_base_t base;
+    unsigned elem_size; // in bytes
+} machine_mem_obj_t;
+
+STATIC void machine_mem_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
+    (void)kind;
+    machine_mem_obj_t *self = self_in;
+    mp_printf(print, "<%u-bit memory>", 8 * self->elem_size);
+}
+
+STATIC mp_obj_t machine_mem_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
+    // TODO support slice index to read/write multiple values at once
+    machine_mem_obj_t *self = self_in;
+    if (value == MP_OBJ_NULL) {
+        // delete
+        return MP_OBJ_NULL; // op not supported
+    } else if (value == MP_OBJ_SENTINEL) {
+        // load
+        mp_uint_t addr = get_read_addr(index, self->elem_size);
+        uint32_t val;
+        switch (self->elem_size) {
+            case 1: val = (*(uint8_t*)addr); break;
+            case 2: val = (*(uint16_t*)addr); break;
+            default: val = (*(uint32_t*)addr); break;
+        }
+        return mp_obj_new_int(val);
+    } else {
+        // store
+        mp_uint_t addr = get_write_addr(index, self->elem_size);
+        uint32_t val = mp_obj_get_int(value);
+        switch (self->elem_size) {
+            case 1: (*(uint8_t*)addr) = val; break;
+            case 2: (*(uint16_t*)addr) = val; break;
+            default: (*(uint32_t*)addr) = val; break;
+        }
+        return mp_const_none;
+    }
+}
+
+STATIC const mp_obj_type_t machine_mem_type = {
+    { &mp_type_type },
+    .name = MP_QSTR_mem,
+    .print = machine_mem_print,
+    .subscr = machine_mem_subscr,
+};
+
+STATIC const machine_mem_obj_t machine_mem8_obj = {{&machine_mem_type}, 1};
+STATIC const machine_mem_obj_t machine_mem16_obj = {{&machine_mem_type}, 2};
+STATIC const machine_mem_obj_t machine_mem32_obj = {{&machine_mem_type}, 4};
+
+STATIC const mp_map_elem_t machine_module_globals_table[] = {
+    { MP_OBJ_NEW_QSTR(MP_QSTR___name__), MP_OBJ_NEW_QSTR(MP_QSTR_machine) },
+
+    { MP_OBJ_NEW_QSTR(MP_QSTR_mem8), (mp_obj_t)&machine_mem8_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_mem16), (mp_obj_t)&machine_mem16_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_mem32), (mp_obj_t)&machine_mem32_obj },
+};
+
+STATIC MP_DEFINE_CONST_DICT(machine_module_globals, machine_module_globals_table);
+
+const mp_obj_module_t mp_module_machine = {
+    .base = { &mp_type_module },
+    .name = MP_QSTR_machine,
+    .globals = (mp_obj_dict_t*)&machine_module_globals,
+};
+
+#endif // MICROPY_PY_MACHINE

py/builtin.h

@@ -101,5 +101,6 @@ extern const mp_obj_module_t mp_module_ure;
 extern const mp_obj_module_t mp_module_uheapq;
 extern const mp_obj_module_t mp_module_uhashlib;
 extern const mp_obj_module_t mp_module_ubinascii;
+extern const mp_obj_module_t mp_module_machine;
 
 #endif // __MICROPY_INCLUDED_PY_BUILTIN_H__

py/mpconfig.h

@@ -620,6 +620,10 @@ typedef double mp_float_t;
 #define MICROPY_PY_UBINASCII (0)
 #endif
 
+#ifndef MICROPY_PY_MACHINE
+#define MICROPY_PY_MACHINE (0)
+#endif
+
 /*****************************************************************************/
 /* Hooks for a port to add builtins                                          */
 

py/objmodule.c

@@ -183,6 +183,9 @@ STATIC const mp_map_elem_t mp_builtin_module_table[] = {
 #if MICROPY_PY_UBINASCII
     { MP_OBJ_NEW_QSTR(MP_QSTR_ubinascii), (mp_obj_t)&mp_module_ubinascii },
 #endif
+#if MICROPY_PY_MACHINE
+    { MP_OBJ_NEW_QSTR(MP_QSTR_machine), (mp_obj_t)&mp_module_machine },
+#endif
 
     // extra builtin modules as defined by a port
     MICROPY_PORT_BUILTIN_MODULES

py/py.mk

@@ -118,6 +118,7 @@ PY_O_BASENAME = \
 	../extmod/moduheapq.o \
 	../extmod/moduhashlib.o \
 	../extmod/modubinascii.o \
+	../extmod/modmachine.o \
 
 # prepend the build destination prefix to the py object files
 PY_O = $(addprefix $(PY_BUILD)/, $(PY_O_BASENAME))

py/qstrdefs.h

@@ -583,3 +583,11 @@ Q(sha256)
 Q(ubinascii)
 Q(hexlify)
 #endif
+
+#if MICROPY_PY_MACHINE
+Q(machine)
+Q(mem)
+Q(mem8)
+Q(mem16)
+Q(mem32)
+#endif

unix/mpconfigport.h

@@ -88,6 +88,7 @@
 #define MICROPY_PY_UHEAPQ           (1)
 #define MICROPY_PY_UHASHLIB         (1)
 #define MICROPY_PY_UBINASCII        (1)
+#define MICROPY_PY_MACHINE          (1)
 
 // Define to MICROPY_ERROR_REPORTING_DETAILED to get function, etc.
 // names in exception messages (may require more RAM).