nuttx/libs
hanzhijian 502feadb3d 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>
2026-07-04 01:59:35 +08:00
..
libbuiltin fix(compiler-rt): avoid duplicate builtins dir on sim 2026-05-13 10:01:26 -03:00
libc stdlib/rand: replace weak LCG with xorshift32 PRNG 2026-07-04 01:59:35 +08:00
libdsp Makefile: Remove make depend files by make distclean 2026-02-16 16:27:57 +01:00
libm libs/libm: correct implementation of truncl if long double is double 2026-07-03 10:32:57 +08:00
libnx include/debug.h: Move to include/nuttx/debug.h 2026-04-07 07:50:06 -03:00
libxx libs\libxx: Fix Make style 2026-03-23 18:16:46 -04:00
CMakeLists.txt libs: migrate to SPDX identifier 2024-10-01 12:25:52 +08:00