Commit 0c43cf91 authored by Paul Sokolovsky's avatar Paul Sokolovsky
Browse files

modstruct: Basic implementation of native struct alignment and types.

parent ef9124f5
......@@ -78,25 +78,54 @@ mp_obj_t mp_binary_get_val_array(char typecode, void *p, int index) {
}
#define is_signed(typecode) (typecode > 'Z')
mp_obj_t mp_binary_get_val_unaligned(char typecode, byte **ptr) {
char type = '<';
mp_obj_t mp_binary_get_val(char struct_type, char val_type, byte **ptr) {
byte *p = *ptr;
uint size = 0, align = 0;
switch (type) {
uint size = 0;
switch (struct_type) {
case '<': case '>':
switch (typecode) {
switch (val_type) {
case 'b': case 'B':
size = 1; break;
case 'h': case 'H':
size = 2; break;
case 'i': case 'I':
size = 4; break;
case 'l': case 'L':
size = 4; break;
}
break;
case '@': {
// TODO:
// The simplest heuristic for alignment is to align by value
// size, but that doesn't work for "bigger than int" types,
// for example, long long may very well have long alignment
// So, we introduce separate alignment handling, but having
// formal support for that is different from actually supporting
// particular (or any) ABI.
uint align = 0;
switch (val_type) {
case 'b': case 'B':
align = size = 1; break;
case 'h': case 'H':
align = size = sizeof(short); break;
case 'i': case 'I':
align = size = sizeof(int); break;
case 'l': case 'L':
align = size = sizeof(long); break;
}
// Make pointer aligned
p = (byte*)(((machine_uint_t)p + align - 1) & ~(align - 1));
#if MP_ENDIANNESS_LITTLE
struct_type = '<';
#else
struct_type = '>';
#endif
break;
}
}
int delta;
if (type == '<') {
if (struct_type == '<') {
delta = -1;
p += size - 1;
} else {
......@@ -104,7 +133,7 @@ mp_obj_t mp_binary_get_val_unaligned(char typecode, byte **ptr) {
}
machine_int_t val = 0;
if (is_signed(typecode) && *p & 0x80) {
if (is_signed(val_type) && *p & 0x80) {
val = -1;
}
for (uint i = 0; i < size; i++) {
......@@ -113,8 +142,8 @@ mp_obj_t mp_binary_get_val_unaligned(char typecode, byte **ptr) {
p += delta;
}
*ptr += size + align;
if (is_signed(typecode)) {
*ptr += size;
if (is_signed(val_type)) {
return mp_obj_new_int(val);
} else {
return mp_obj_new_int_from_uint(val);
......
......@@ -3,6 +3,6 @@
#define BYTEARRAY_TYPECODE 0
int mp_binary_get_size(char typecode);
mp_obj_t mp_binary_get_val(char typecode, void *p, int index);
mp_obj_t mp_binary_get_val_unaligned(char typecode, byte **ptr);
void mp_binary_set_val(char typecode, void *p, int index, mp_obj_t val_in);
mp_obj_t mp_binary_get_val_array(char typecode, void *p, int index);
mp_obj_t mp_binary_get_val(char struct_type, char val_type, byte **ptr);
void mp_binary_set_val_array(char typecode, void *p, int index, mp_obj_t val_in);
......@@ -37,7 +37,7 @@ STATIC uint calcsize_items(const char *fmt) {
STATIC mp_obj_t struct_calcsize(mp_obj_t fmt_in) {
const char *fmt = mp_obj_str_get_str(fmt_in);
char fmt_type = get_fmt_type(&fmt);
assert(fmt_type == '<' || fmt_type == '>'); (void)fmt_type;
(void)fmt_type;
machine_uint_t size;
for (size = 0; *fmt; fmt++) {
int sz = mp_binary_get_size(*fmt);
......@@ -53,7 +53,6 @@ STATIC mp_obj_t struct_unpack(mp_obj_t fmt_in, mp_obj_t data_in) {
// TODO: "The buffer must contain exactly the amount of data required by the format (len(bytes) must equal calcsize(fmt))."
const char *fmt = mp_obj_str_get_str(fmt_in);
char fmt_type = get_fmt_type(&fmt);
assert(fmt_type == '<' || fmt_type == '>'); (void)fmt_type;
uint size = calcsize_items(fmt);
mp_obj_tuple_t *res = mp_obj_new_tuple(size, NULL);
buffer_info_t bufinfo;
......@@ -61,7 +60,7 @@ STATIC mp_obj_t struct_unpack(mp_obj_t fmt_in, mp_obj_t data_in) {
byte *p = bufinfo.buf;
for (uint i = 0; i < size; i++) {
mp_obj_t item = mp_binary_get_val_unaligned(*fmt++, &p);
mp_obj_t item = mp_binary_get_val(fmt_type, *fmt++, &p);
res->items[i] = item;
}
return res;
......
......@@ -3,3 +3,6 @@ print(struct.calcsize("<bI"))
print(struct.unpack("<bI", b"\x80\0\0\x01\0"))
print(struct.calcsize(">bI"))
print(struct.unpack(">bI", b"\x80\0\0\x01\0"))
# 32-bit little-endian specific
#print(struct.unpack("bI", b"\x80\xaa\x55\xaa\0\0\x01\0"))
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