Commit graph

11 commits

Author SHA1 Message Date
hanzhijian
9e467388de stdlib/rand: replace weak LCG with xorshift32 PRNG
The existing first-order LCG (seed = 470001 * seed % 999563) has several
quality problems:
- Output range limited to [1, 999562] (~20 bits) instead of full 32-bit
- Lower bits have very short periods (8-bit period = 1, 16-bit = 105)
- Overall period only ~1M, far too short for many applications
- Causes mbedtls_rsa_gen_key to loop forever when rand() consumption
  aligns with the cycle length (issue #16760)

Replace the entire order-based LCG implementation (CONFIG_LIBC_RAND_ORDER
0-3) with Marsaglia's xorshift32:
- Full 32-bit output range
- Period 2^32 - 1 (~4.29 billion)
- Fast: just three XOR/shift operations
- No floating-point math needed
- No CONFIG_LIBC_RAND_ORDER configuration required

Remove the CONFIG_LIBC_RAND_ORDER Kconfig option and clean up all
defconfig references (12 boards) and related comments.

Signed-off-by: hanzhijian <hanzhijian@zepp.com>
2026-07-03 15:08:12 +08:00
Alin Jerpelea
6b5dddd5d7 libs/libc: migrate to SPDX identifier
Most tools used for compliance and SBOM generation use SPDX identifiers
This change brings us a step closer to an easy SBOM generation.

Signed-off-by: Alin Jerpelea <alin.jerpelea@sony.com>
2024-10-01 12:25:52 +08:00
anjiahao
3fdff878bc libc:Add macro restrictions to code that uses floating point numbers
Signed-off-by: anjiahao <anjiahao@xiaomi.com>
2024-08-21 13:33:45 +08:00
dongjiuzhu1
5d09b4cbd0 libc/rand_r: support rand_r api
refs to https://pubs.opengroup.org/onlinepubs/7908799/xsh/rand.html

Signed-off-by: dongjiuzhu1 <dongjiuzhu1@xiaomi.com>
2023-07-29 07:28:23 -07:00
Xiang Xiao
5025fbef8d Rename LIB_ to LIBC_ for all libc Kconfig
follow other libc component naming convention

Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
2021-08-05 19:45:24 +02:00
Xiang Xiao
3f9908f7d1 Remove the unnecessary math.h inclusion
or move from header file to source file since math.h doesn't always exist

Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
2021-04-12 22:58:23 -04:00
Alin Jerpelea
b5d4a01821 libs: Author Gregory Nutt: update licenses to Apache
Gregory Nutt has submitted the SGA and we can migrate the licenses
 to Apache.

Signed-off-by: Alin Jerpelea <alin.jerpelea@sony.com>
2021-03-03 18:52:53 -08:00
Xiang Xiao
d17b963bca libc: Move double_t typedef from sys/types.h to math.h
specified here:
https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/math.h.html

Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
Change-Id: I3497a73908301d999cf1cfc4a66552a7ca4868c6
2020-06-29 13:37:41 +01:00
Xiang Xiao
6a3c2aded6 Fix wait loop and void cast (#24)
* Simplify EINTR/ECANCEL error handling

1. Add semaphore uninterruptible wait function
2 .Replace semaphore wait loop with a single uninterruptible wait
3. Replace all sem_xxx to nxsem_xxx

* Unify the void cast usage

1. Remove void cast for function because many place ignore the returned value witout cast
2. Replace void cast for variable with UNUSED macro
2020-01-02 10:54:43 -06:00
Gregory Nutt
12d216fa5e Fix another error found in build testing. 2018-07-19 15:19:36 -06:00
Gregory Nutt
cf99fb40c9 This commit moves all of the libraries under a common directory called libs/. This most certainly break libcxx and uClibc++ for now.
Squashed commit of the following:

    libs/libxx:  Fix some confusing in naming.  If the directory is called libxx, then the library must be libxx.a (unless perhaps LIBCXX is selected).
    libs/:  Fix paths in moved library directories.
    libs:  Brute force move of libc, libnx, and libxx to libs.  Cannot yet build it in that configuration.
2018-05-29 13:21:26 -06:00
Renamed from libc/stdlib/lib_srand.c (Browse further)