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modstruct: Fix .calcsize() to account for struct type/alignment.

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This commit is contained in:
Paul Sokolovsky
2014-04-19 01:25:49 +03:00
parent 5695e07256
commit 1355cf42f2
4 changed files with 65 additions and 80 deletions
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131
py/binary.c
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@@ -1,4 +1,5 @@
#include <stdint.h>
#include <stdlib.h>
#include <assert.h>
#include "misc.h"
@@ -9,34 +10,52 @@
// Helpers to work with binary-encoded data
int mp_binary_get_size(char typecode) {
// This assumes that unsigned and signed types are of the same type,
// which is invariant for [u]intN_t.
switch (typecode) {
case BYTEARRAY_TYPECODE:
case 'b':
case 'B':
return sizeof(int8_t);
case 'h':
case 'H':
return sizeof(int16_t);
case 'i':
case 'I':
return sizeof(int32_t);
case 'l':
case 'L':
return sizeof(int32_t);
case 'q':
case 'Q':
return sizeof(long long);
#if MICROPY_ENABLE_FLOAT
case 'f':
return sizeof(float);
case 'd':
return sizeof(double);
#endif
int mp_binary_get_size(char struct_type, char val_type, uint *palign) {
int size = 0;
int align = 1;
switch (struct_type) {
case '<': case '>':
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;
case 'q': case 'Q':
size = 8; 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.
switch (val_type) {
case BYTEARRAY_TYPECODE:
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;
case 'q': case 'Q':
// TODO: This is for x86
align = sizeof(int); size = sizeof(long long); break;
}
}
}
return -1;
if (palign != NULL) {
*palign = align;
}
return size;
}
mp_obj_t mp_binary_get_val_array(char typecode, void *p, int index) {
@@ -80,53 +99,17 @@ 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(char struct_type, char val_type, byte **ptr) {
byte *p = *ptr;
uint size = 0;
switch (struct_type) {
case '<': case '>':
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;
case 'q': case 'Q':
size = 8; 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;
case 'q': case 'Q':
// TODO: This is for x86
align = sizeof(int); size = sizeof(long 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;
}
uint align;
int size = mp_binary_get_size(struct_type, val_type, &align);
if (struct_type == '@') {
// Make pointer aligned
p = (byte*)(((machine_uint_t)p + align - 1) & ~(align - 1));
#if MP_ENDIANNESS_LITTLE
struct_type = '<';
#else
struct_type = '>';
#endif
}
int delta;