unix: Add example of dynamic loadable native C code.

dpgeorge · dpgeorge · commit 81dee3ea5cfa · 2019-03-08T17:20:17.000+11:00
Build with:

    $ ./mk_native.sh

Execute with:

    $ ./micropython
    import native_ex
    native_ex.foo()
diff --git a/ports/unix/mk_native.sh b/ports/unix/mk_native.sh
@@ -0,0 +1,16 @@
+#!/bin/sh
+
+# x64
+CFLAGS=-fno-stack-protector
+
+# thumb
+#CROSS=arm-none-eabi-
+#CFLAGS=-mthumb
+
+# xtensa
+#CROSS=xtensa-lx106-elf-
+#CFLAGS=-mforce-l32
+
+${CROSS}gcc -fPIC -fPIE $CFLAGS -std=c99 -Os -c native_ex.c -o native_ex.o
+${CROSS}ld -T native_ex.ld native_ex.o -o native_ex.elf
+${CROSS}objcopy -O binary -j .header -j .text -j .trailer native_ex.elf native_ex.mpy
diff --git a/ports/unix/native_ex.c b/ports/unix/native_ex.c
@@ -0,0 +1,106 @@
+#include <stdint.h>
+#include <stddef.h>
+
+#define HEADER_SIZE (48)
+#define CODE_SIZE (256 - HEADER_SIZE)
+
+#define UINT_HI(x) (0x80 | ((x) >> 7))
+#define UINT_LO(x) ((x) & 0x7f)
+
+#define MP_BC_LOAD_CONST_NONE    (0x11)
+#define MP_BC_STORE_GLOBAL       (0x25) // qstr
+#define MP_BC_RETURN_VALUE       (0x5b)
+#define MP_BC_MAKE_FUNCTION      (0x60) // uint
+
+#define MP_OBJ_NEW_SMALL_INT(x) ((x) << 1 | 1)
+
+typedef enum {
+    MP_CODE_BYTECODE = 2,
+    MP_CODE_NATIVE_PY,
+    MP_CODE_NATIVE_VIPER,
+    MP_CODE_NATIVE_ASM,
+} mp_raw_code_kind_t;
+
+struct _mp_f_table_t {
+    uintptr_t none_obj;
+    uintptr_t false_obj;
+    uintptr_t true_obj;
+    uintptr_t pad0[2];
+    uintptr_t (*swap_globals)(uintptr_t new_globals);
+    uintptr_t (*load_name)(uint16_t qst);
+    uintptr_t pad1[13];
+    uintptr_t (*new_list)(size_t n, uintptr_t *items);
+    uintptr_t pad2[6];
+    uintptr_t (*call_function_n_kw)(uintptr_t fun_in, size_t n_args_kw, const uintptr_t *args);
+};
+
+typedef struct _mp_obj_fun_bc_t {
+    uintptr_t base;
+    uintptr_t globals;
+    const void *fun_data;
+    const void **const_table;
+} mp_obj_fun_bc_t;
+
+const uint8_t header[HEADER_SIZE] __attribute__((section(".header"))) = {
+    'M', 4, 3 | 2 << 2, 31, 32, // x64
+    //'M', 4, 2 | 5 << 2, 31, 32, // thumb
+    //'M', 4, 2 | 9 << 2, 31, 32, // xtensa
+
+    ((12 + 10) << 2) | (MP_CODE_BYTECODE - MP_CODE_BYTECODE), // n bytes
+
+    // prelude
+    1, // n_state
+    0, // n_exc_stack
+    0, // scope_flags
+    0, // n_pos_args
+    0, // n_kwonly_args
+    0, // n_def_pos_args
+    5, // code_info_size (incl this member)
+    0, 0, // simple_name
+    0, 0, // source_file
+    255, // end of list sentinel
+
+    // bytecode
+    MP_BC_MAKE_FUNCTION, 0,
+    MP_BC_STORE_GLOBAL, 3 << 1, 'f', 'o', 'o',
+    MP_BC_LOAD_CONST_NONE,
+    MP_BC_RETURN_VALUE,
+    0, 0, 0, // padding
+
+    6 << 1, 'n', 'a', 't', 'i', 'v', 'e', // simple_name
+    6 << 1, 'n', 'a', 't', 'i', 'v', 'e', // source_file
+    0, // n_obj
+    1, // n_raw_code
+
+    // raw_code
+    UINT_HI(((CODE_SIZE + 2) << 2) | (MP_CODE_NATIVE_VIPER - MP_CODE_BYTECODE)),
+    UINT_LO(((CODE_SIZE + 2) << 2) | (MP_CODE_NATIVE_VIPER - MP_CODE_BYTECODE)),
+};
+
+const uint8_t trailer[] __attribute__((section(".trailer"))) = {
+    0, 0, // qstr0
+    1, // n_qstr
+    UINT_HI(CODE_SIZE << 2), UINT_LO(CODE_SIZE << 2), 5 << 1, 'p', 'r', 'i', 'n', 't', // qstr0
+    0, // scope_flags
+    0, // n_obj
+    0, // n_raw_code
+};
+
+uintptr_t foo(mp_obj_fun_bc_t *self, uintptr_t n_args, uintptr_t n_kw, uintptr_t *args) {
+    uint16_t *qstr_table = (uint16_t*)(self->fun_data + CODE_SIZE);
+    const struct _mp_f_table_t *f = (const void*)self->const_table[0];
+
+    uintptr_t old_globals = f->swap_globals(self->globals);
+
+    uintptr_t print = f->load_name(qstr_table[0]);
+
+    for (int i = 0; i < 10; ++i) {
+        uintptr_t args[2] = {MP_OBJ_NEW_SMALL_INT(i), (i & 1) ? f->true_obj : f->false_obj};
+        f->call_function_n_kw(print, 2, &args[0]);
+    }
+
+    f->swap_globals(old_globals);
+
+    uintptr_t list[2] = {MP_OBJ_NEW_SMALL_INT(42), MP_OBJ_NEW_SMALL_INT(n_args)};
+    return f->new_list(2, list);
+}
diff --git a/ports/unix/native_ex.ld b/ports/unix/native_ex.ld
@@ -0,0 +1,24 @@
+MEMORY
+{
+    FLASH (rx) : ORIGIN = 0x00000000, LENGTH = 32K
+}
+
+SECTIONS
+{
+    .header :
+    {
+        KEEP(header*(.rodata*))
+    } >FLASH
+
+    .text :
+    {
+        KEEP(*(.text*))
+        KEEP(*(.rodata*))
+    } >FLASH
+
+    .trailer :
+    {
+        . = ALIGN(256);
+        KEEP(trailer*(.rodata*))
+    } >FLASH
+}
