10000 Merge pull request #66 from robert-hh/struct · pycom/pycom-micropython-sigfox@15fcfcf · GitHub
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Merge pull request #66 from robert-hh/struct
ustruct: Pull in ustruct module from the Micropython.org tree
2 parents 01cc316 + a5eb2d8 commit 15fcfcf

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‎py/modstruct.c

Lines changed: 44 additions & 46 deletions
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
11
/*
2-
* This file is part of the Micro Python project, http://micropython.org/
2+
* This file is part of the MicroPython project, http://micropython.org/
33
*
44
* The MIT License (MIT)
55
*
@@ -82,47 +82,38 @@ STATIC mp_uint_t get_fmt_num(const char **p) {
8282
return val;
8383
}
8484

85-
STATIC uint calcsize_items(const char *fmt) {
86-
uint cnt = 0;
87-
while (*fmt) {
88-
int num = 1;
89-
if (unichar_isdigit(*fmt)) {
90-
num = get_fmt_num(&fmt);
91-
if (*fmt == 's') {
92-
num = 1;
93-
}
94-
}
95-
cnt += num;
96-
fmt++;
97-
}
98-
return cnt;
99-
}
100-
101-
STATIC mp_obj_t struct_calcsize(mp_obj_t fmt_in) {
102-
const char *fmt = mp_obj_str_get_str(fmt_in);
85+
STATIC size_t calc_size_items(const char *fmt, size_t *total_sz) {
10386
char fmt_type = get_fmt_type(&fmt);
104-
mp_uint_t size;
87+
size_t total_cnt = 0;
88+
size_t size;
10589
for (size = 0; *fmt; fmt++) {
10690
mp_uint_t cnt = 1;
10791
if (unichar_isdigit(*fmt)) {
10892
cnt = get_fmt_num(&fmt);
10993
}
11094

11195
if (*fmt == 's') {
96+
total_cnt += 1;
11297
size += cnt;
11398
} else {
99+
total_cnt += cnt;
114100
mp_uint_t align;
115101
size_t sz = mp_binary_get_size(fmt_type, *fmt, &align);
116-
if (sz == 0) {
117-
mp_raise_ValueError("unsupported format");
118-
}
119102
while (cnt--) {
120103
// Apply alignment
121104
size = (size + align - 1) & ~(align - 1);
122105
size += sz;
123106
}
124107
}
125108
}
109+
*total_sz = size;
110+
return total_cnt;
111+
}
112+
113+
STATIC mp_obj_t struct_calcsize(mp_obj_t fmt_in) {
114+
const char *fmt = mp_obj_str_get_str(fmt_in);
115+
size_t size;
116+
calc_size_items(fmt, &size);
126117
return MP_OBJ_NEW_SMALL_INT(size);
127118
}
128119
MP_DEFINE_CONST_FUN_OBJ_1(struct_calcsize_obj, struct_calcsize);
@@ -133,8 +124,9 @@ STATIC mp_obj_t struct_unpack_from(size_t n_args, const mp_obj_t *args) {
133124
// Since we implement unpack and unpack_from using the same function
134125
// we relax the "exact" requirement, and only implement "big enough".
135126
const char *fmt = mp_obj_str_get_str(args[0]);
127+
size_t total_sz;
128+
size_t num_items = calc_size_items(fmt, &total_sz);
136129
char fmt_type = get_fmt_type(&fmt);
137-
uint num_items = calcsize_items(fmt);
138130
mp_obj_tuple_t *res = MP_OBJ_TO_PTR(mp_obj_new_tuple(num_items, NULL));
139131
mp_buffer_info_t bufinfo;
140132
mp_get_buffer_raise(args[1], &bufinfo, MP_BUFFER_READ);
@@ -155,21 +147,23 @@ STATIC mp_obj_t struct_unpack_from(size_t n_args, const mp_obj_t *args) {
155147
p += offset;
156148
}
157149

158-
for (uint i = 0; i < num_items;) {
159-
mp_uint_t sz = 1;
150+
// Check that the input buffer is big enough to unpack all the values
151+
if (p + total_sz > end_p) {
152+
mp_raise_ValueError("buffer too small");
153+
}
154+
155+
for (size_t i = 0; i < num_items;) {
156+
mp_uint_t cnt = 1;
160157
if (unichar_isdigit(*fmt)) {
161-
sz = get_fmt_num(&fmt);
162-
}
163-
if (p + sz > end_p) {
164-
mp_raise_ValueError("buffer too small");
158+
cnt = get_fmt_num(&fmt);
165159
}
166160
mp_obj_t item;
167161
if (*fmt == 's') {
168-
item = mp_obj_new_bytes(p, sz);
169-
p += sz;
162+
item = mp_obj_new_bytes(p, cnt);
163+
p += cnt;
170164
res->items[i++] = item;
171165
} else {
172-
while (sz--) {
166+
while (cnt--) {
173167
item = mp_binary_get_val(fmt_type, *fmt, &p);
174168
res->items[i++] = item;
175169
}
@@ -180,36 +174,35 @@ STATIC mp_obj_t struct_unpack_from(size_t n_args, const mp_obj_t *args) {
180174
}
181175
MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(struct_unpack_from_obj, 2, 3, struct_unpack_from);
182176

183-
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) {
177+
// This function assumes there is enough room in p to store all the values
178+
STATIC void struct_pack_into_internal(mp_obj_t fmt_in, byte *p, size_t n_args, const mp_obj_t *args) {
184179
const char *fmt = mp_obj_str_get_str(fmt_in);
185180
char fmt_type = get_fmt_type(&fmt);
186181

187182
size_t i;
188183
for (i = 0; i < n_args;) {
189-
mp_uint_t sz = 1;
184+
mp_uint_t cnt = 1;
190185
if (*fmt == '\0') {
191186
// more arguments given than used by format string; CPython raises struct.error here
192187
break;
193188
}
194189
if (unichar_isdigit(*fmt)) {
195-
sz = get_fmt_num(&fmt);
196-
}
197-
if (p + sz > end_p) {
198-
mp_raise_ValueError("buffer too small");
190+
cnt = get_fmt_num(&fmt);
199191
}
200192

201193
if (*fmt == 's') {
202194
mp_buffer_info_t bufinfo;
203195
mp_get_buffer_raise(args[i++], &bufinfo, MP_BUFFER_READ);
204-
mp_uint_t to_copy = sz;
196+
mp_uint_t to_copy = cnt;
205197
if (bufinfo.len < to_copy) {
206198
to_copy = bufinfo.len;
207199
}
208200
memcpy(p, bufinfo.buf, to_copy);
209-
memset(p + to_copy, 0, sz - to_copy);
210-
p += sz;
201+
memset(p + to_copy, 0, cnt - to_copy);
202+
p += cnt;
211203
} else {
212-
while (sz--) {
204+
// If we run out of args then we just finish; CPython would raise struct.error
205+
while (cnt-- && i < n_args) {
213206
mp_binary_set_val(fmt_type, *fmt, args[i++], &p);
214207
}
215208
}
@@ -224,8 +217,7 @@ STATIC mp_obj_t struct_pack(size_t n_args, const mp_obj_t *args) {
224217
vstr_init_len(&vstr, size);
225218
byte *p = (byte*)vstr.buf;
226219
memset(p, 0, size);
227-
byte *end_p = &p[size];
228-
struct_pack_into_internal(args[0], p, end_p, n_args - 1, &args[1]);
220+
struct_pack_into_internal(args[0], p, n_args - 1, &args[1]);
229221
return mp_obj_new_str_from_vstr(&mp_type_bytes, &vstr);
230222
}
231223
MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(struct_pack_obj, 1, MP_OBJ_FUN_ARGS_MAX, struct_pack);
@@ -245,7 +237,13 @@ STATIC mp_obj_t struct_pack_into(size_t n_args, const mp_obj_t *args) {
245237
byte *end_p = &p[bufinfo.len];
246238
p += offset;
247239

248-
struct_pack_into_internal(args[0], p, end_p, n_args - 3, &args[3]);
240+
// Check that the output buffer is big enough to hold all the values
241+
mp_int_t sz = MP_OBJ_SMALL_INT_VALUE(struct_calcsize(args[0]));
242+
if (p + sz > end_p) {
243+
mp_raise_ValueError("buffer too small");
244+
}
245+
246+
struct_pack_into_internal(args[0], p, n_args - 3, &args[3]);
249247
return mp_const_none;
250248
}
251249
MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(struct_pack_into_obj, 3, MP_OBJ_FUN_ARGS_MAX, struct_pack_into);

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