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/**********************************************************************
* Copyright (c) 2017 Andrew Poelstra *
* Distributed under the MIT software license, see the accompanying *
* file COPYING or http://www.opensource.org/licenses/mit-license.php.*
**********************************************************************/
#ifndef _SECP256K1_SCRATCH_IMPL_H_
#define _SECP256K1_SCRATCH_IMPL_H_
#include "scratch.h"
/* Using 16 bytes alignment because common architectures never have alignment
* requirements above 8 for any of the types we care about. In addition we
* leave some room because currently we don't care about a few bytes.
* TODO: Determine this at configure time. */
#define ALIGNMENT 16
static secp256k1_scratch* secp256k1_scratch_create(const secp256k1_callback* error_callback, size_t max_size) {
secp256k1_scratch* ret = (secp256k1_scratch*)checked_malloc(error_callback, sizeof(*ret));
if (ret != NULL) {
memset(ret, 0, sizeof(*ret));
ret->max_size = max_size;
ret->error_callback = error_callback;
}
return ret;
}
static void secp256k1_scratch_destroy(secp256k1_scratch* scratch) {
if (scratch != NULL) {
VERIFY_CHECK(scratch->frame == 0);
free(scratch);
}
}
static size_t secp256k1_scratch_max_allocation(const secp256k1_scratch* scratch, size_t objects) {
size_t i = 0;
size_t allocated = 0;
for (i = 0; i < scratch->frame; i++) {
allocated += scratch->frame_size[i];
}
if (scratch->max_size - allocated <= objects * ALIGNMENT) {
return 0;
}
return scratch->max_size - allocated - objects * ALIGNMENT;
}
static int secp256k1_scratch_allocate_frame(secp256k1_scratch* scratch, size_t n, size_t objects) {
VERIFY_CHECK(scratch->frame < SECP256K1_SCRATCH_MAX_FRAMES);
if (n <= secp256k1_scratch_max_allocation(scratch, objects)) {
n += objects * ALIGNMENT;
scratch->data[scratch->frame] = checked_malloc(scratch->error_callback, n);
if (scratch->data[scratch->frame] == NULL) {
return 0;
}
scratch->frame_size[scratch->frame] = n;
scratch->offset[scratch->frame] = 0;
scratch->frame++;
return 1;
} else {
return 0;
}
}
static void secp256k1_scratch_deallocate_frame(secp256k1_scratch* scratch) {
VERIFY_CHECK(scratch->frame > 0);
scratch->frame -= 1;
free(scratch->data[scratch->frame]);
}
static void *secp256k1_scratch_alloc(secp256k1_scratch* scratch, size_t size) {
void *ret;
size_t frame = scratch->frame - 1;
size = ((size + ALIGNMENT - 1) / ALIGNMENT) * ALIGNMENT;
if (scratch->frame == 0 || size + scratch->offset[frame] > scratch->frame_size[frame]) {
return NULL;
}
ret = (void *) ((unsigned char *) scratch->data[frame] + scratch->offset[frame]);
memset(ret, 0, size);
scratch->offset[frame] += size;
return ret;
}
#endif