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