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ustruct: Pull in ustruct module from the Micropython.org tree #66

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Sep 21, 2017
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ustruct: Pull in ustruct module from the Micropython.org tree #66

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90 changes: 44 additions & 46 deletions py/modstruct.c
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
/*
* This file is part of the Micro Python project, http://micropython.org/
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
Expand Down Expand Up @@ -82,47 +82,38 @@ STATIC mp_uint_t get_fmt_num(const char **p) {
return val;
}

STATIC uint calcsize_items(const char *fmt) {
uint cnt = 0;
while (*fmt) {
int num = 1;
if (unichar_isdigit(*fmt)) {
num = get_fmt_num(&fmt);
if (*fmt == 's') {
num = 1;
}
}
cnt += num;
fmt++;
}
return cnt;
}

STATIC mp_obj_t struct_calcsize(mp_obj_t fmt_in) {
const char *fmt = mp_obj_str_get_str(fmt_in);
STATIC size_t calc_size_items(const char *fmt, size_t *total_sz) {
char fmt_type = get_fmt_type(&fmt);
mp_uint_t size;
size_t total_cnt = 0;
size_t size;
for (size = 0; *fmt; fmt++) {
mp_uint_t cnt = 1;
if (unichar_isdigit(*fmt)) {
cnt = get_fmt_num(&fmt);
}

if (*fmt == 's') {
total_cnt += 1;
size += cnt;
} else {
total_cnt += cnt;
mp_uint_t align;
size_t sz = mp_binary_get_size(fmt_type, *fmt, &align);
if (sz == 0) {
mp_raise_ValueError("unsupported format");
}
while (cnt--) {
// Apply alignment
size = (size + align - 1) & ~(align - 1);
size += sz;
}
}
}
*total_sz = size;
return total_cnt;
}

STATIC mp_obj_t struct_calcsize(mp_obj_t fmt_in) {
const char *fmt = mp_obj_str_get_str(fmt_in);
size_t size;
calc_size_items(fmt, &size);
return MP_OBJ_NEW_SMALL_INT(size);
}
MP_DEFINE_CONST_FUN_OBJ_1(struct_calcsize_obj, struct_calcsize);
Expand All @@ -133,8 +124,9 @@ STATIC mp_obj_t struct_unpack_from(size_t n_args, const mp_obj_t *args) {
// Since we implement unpack and unpack_from using the same function
// we relax the "exact" requirement, and only implement "big enough".
const char *fmt = mp_obj_str_get_str(args[0]);
size_t total_sz;
size_t num_items = calc_size_items(fmt, &total_sz);
char fmt_type = get_fmt_type(&fmt);
uint num_items = calcsize_items(fmt);
mp_obj_tuple_t *res = MP_OBJ_TO_PTR(mp_obj_new_tuple(num_items, NULL));
mp_buffer_info_t bufinfo;
mp_get_buffer_raise(args[1], &bufinfo, MP_BUFFER_READ);
Expand All @@ -155,21 +147,23 @@ STATIC mp_obj_t struct_unpack_from(size_t n_args, const mp_obj_t *args) {
p += offset;
}

for (uint i = 0; i < num_items;) {
mp_uint_t sz = 1;
// Check that the input buffer is big enough to unpack all the values
if (p + total_sz > end_p) {
mp_raise_ValueError("buffer too small");
}

for (size_t i = 0; i < num_items;) {
mp_uint_t cnt = 1;
if (unichar_isdigit(*fmt)) {
sz = get_fmt_num(&fmt);
}
if (p + sz > end_p) {
mp_raise_ValueError("buffer too small");
cnt = get_fmt_num(&fmt);
}
mp_obj_t item;
if (*fmt == 's') {
item = mp_obj_new_bytes(p, sz);
p += sz;
item = mp_obj_new_bytes(p, cnt);
p += cnt;
res->items[i++] = item;
} else {
while (sz--) {
while (cnt--) {
item = mp_binary_get_val(fmt_type, *fmt, &p);
res->items[i++] = item;
}
Expand All @@ -180,36 +174,35 @@ STATIC mp_obj_t struct_unpack_from(size_t n_args, const mp_obj_t *args) {
}
MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(struct_unpack_from_obj, 2, 3, struct_unpack_from);

STATIC void struct_pack_into_internal(mp_obj_t fmt_in, byte *p, byte* end_p, size_t n_args, const mp_obj_t *args) {
// This function assumes there is enough room in p to store all the values
STATIC void struct_pack_into_internal(mp_obj_t fmt_in, byte *p, size_t n_args, const mp_obj_t *args) {
const char *fmt = mp_obj_str_get_str(fmt_in);
char fmt_type = get_fmt_type(&fmt);

size_t i;
for (i = 0; i < n_args;) {
mp_uint_t sz = 1;
mp_uint_t cnt = 1;
if (*fmt == '\0') {
// more arguments given than used by format string; CPython raises struct.error here
break;
}
if (unichar_isdigit(*fmt)) {
sz = get_fmt_num(&fmt);
}
if (p + sz > end_p) {
mp_raise_ValueError("buffer too small");
cnt = get_fmt_num(&fmt);
}

if (*fmt == 's') {
mp_buffer_info_t bufinfo;
mp_get_buffer_raise(args[i++], &bufinfo, MP_BUFFER_READ);
mp_uint_t to_copy = sz;
mp_uint_t to_copy = cnt;
if (bufinfo.len < to_copy) {
to_copy = bufinfo.len;
}
memcpy(p, bufinfo.buf, to_copy);
memset(p + to_copy, 0, sz - to_copy);
p += sz;
memset(p + to_copy, 0, cnt - to_copy);
p += cnt;
} else {
while (sz--) {
// If we run out of args then we just finish; CPython would raise struct.error
while (cnt-- && i < n_args) {
mp_binary_set_val(fmt_type, *fmt, args[i++], &p);
}
}
Expand All @@ -224,8 +217,7 @@ STATIC mp_obj_t struct_pack(size_t n_args, const mp_obj_t *args) {
vstr_init_len(&vstr, size);
byte *p = (byte*)vstr.buf;
memset(p, 0, size);
byte *end_p = &p[size];
struct_pack_into_internal(args[0], p, end_p, n_args - 1, &args[1]);
struct_pack_into_internal(args[0], p, n_args - 1, &args[1]);
return mp_obj_new_str_from_vstr(&mp_type_bytes, &vstr);
}
MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(struct_pack_obj, 1, MP_OBJ_FUN_ARGS_MAX, struct_pack);
Expand All @@ -245,7 +237,13 @@ STATIC mp_obj_t struct_pack_into(size_t n_args, const mp_obj_t *args) {
byte *end_p = &p[bufinfo.len];
p += offset;

struct_pack_into_internal(args[0], p, end_p, n_args - 3, &args[3]);
// Check that the output buffer is big enough to hold all the values
mp_int_t sz = MP_OBJ_SMALL_INT_VALUE(struct_calcsize(args[0]));
if (p + sz > end_p) {
mp_raise_ValueError("buffer too small");
}

struct_pack_into_internal(args[0], p, n_args - 3, &args[3]);
return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(struct_pack_into_obj, 3, MP_OBJ_FUN_ARGS_MAX, struct_pack_into);
Expand Down