abawo/pico-sdk
3
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Add pico_rand library (#1111)

Browse Source 
Add a general purpose random number generator via pico_rand library. which tries to use as much real entropy as possible mixed into a PRNG

Co-authored-by: graham sanderson <graham.sanderson@raspberrypi.com>
This commit is contained in:
andygpz11
2023-01-26 19:25:27 +00:00
committed by GitHub
parent 67af83f069
commit b70f984f2a
12 changed files with 505 additions and 42 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
src/rp2_common/pico_lwip/CMakeLists.txt
View File

@ -46,7 +46,6 @@ if (EXISTS ${PICO_LWIP_PATH}/${LWIP_TEST_PATH})
${PICO_LWIP_PATH}/src/core/tcp_out.c
${PICO_LWIP_PATH}/src/core/timeouts.c
${PICO_LWIP_PATH}/src/core/udp.c
${CMAKE_CURRENT_LIST_DIR}/lwip_random.c
)
target_include_directories(pico_lwip_core INTERFACE
${PICO_LWIP_PATH}/src/include)
@ -274,7 +273,8 @@ if (EXISTS ${PICO_LWIP_PATH}/${LWIP_TEST_PATH})
target_link_libraries(pico_lwip_nosys INTERFACE
pico_async_context_base
pico_lwip_arch
pico_lwip)
pico_lwip
pico_rand)
if (NOT PICO_LWIP_CONTRIB_PATH)
set(PICO_LWIP_CONTRIB_PATH ${PICO_LWIP_PATH}/contrib)

12
src/rp2_common/pico_lwip/include/arch/cc.h
View File

@ -86,14 +86,8 @@ void pico_lwip_custom_unlock_tcpip_core(void);
#endif
#ifndef LWIP_RAND
#ifdef __cplusplus
extern "C" {
#endif
unsigned int pico_lwip_rand(void);
#ifdef __cplusplus
}
#endif
// Use ROSC based random number generation, more for the fact that rand() may not be seeded, than anything else
#define LWIP_RAND pico_lwip_rand
#include "pico/rand.h"
// Use the pico_rand library which goes to reasonable lengths to try to provide good entropy
#define LWIP_RAND() get_rand_32()
#endif
#endif /* __CC_H__ */

29
src/rp2_common/pico_lwip/lwip_random.c
View File

@ -1,29 +0,0 @@
/*
* Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#include "pico.h"
#include "hardware/structs/rosc.h"
static uint8_t pico_lwip_random_byte(int cycles) {
static uint8_t byte;
assert(cycles >= 8);
assert(rosc_hw->status & ROSC_STATUS_ENABLED_BITS);
for(int i=0;i<cycles;i++) {
// picked a fairly arbitrary polynomial of 0x35u - this doesn't have to be crazily uniform.
byte = ((byte << 1) | rosc_hw->randombit) ^ (byte & 0x80u ? 0x35u : 0);
// delay a little because the random bit is a little slow
busy_wait_at_least_cycles(30);
}
return byte;
}
unsigned int pico_lwip_rand(void) {
uint32_t value = 0;
for (int i = 0; i < 4; i++) {
value = (value << 8u) | pico_lwip_random_byte(32);
}
return value;
}