diff options
Diffstat (limited to 'src/secp256k1/src/scratch_impl.h')
-rw-r--r-- | src/secp256k1/src/scratch_impl.h | 86 |
1 files changed, 86 insertions, 0 deletions
diff --git a/src/secp256k1/src/scratch_impl.h b/src/secp256k1/src/scratch_impl.h new file mode 100644 index 0000000000..abed713b21 --- /dev/null +++ b/src/secp256k1/src/scratch_impl.h @@ -0,0 +1,86 @@ +/********************************************************************** + * 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 |