random.c

来自「嵌入式操作系统内核」· C语言 代码 · 共 41 行

#include <sos.h>
#include <sos_info.h>
#include <random.h>

typedef struct {
    uint16_t shiftReg;
    uint16_t initSeed;
    uint16_t mask;
} RandomState;

static RandomState randomst;

void random_init(){
    HAS_CRITICAL_SECTION;
    ENTER_CRITICAL_SECTION();
    randomst.shiftReg = (uint16_t)(119 * 119 * (node_address + 1));
    randomst.initSeed = randomst.shiftReg;
    randomst.mask = (uint16_t)(137 * 29 * (node_address + 1));
    LEAVE_CRITICAL_SECTION();
}

uint16_t ker_rand() {
    HAS_CRITICAL_SECTION;
    bool endbit;
    uint16_t tmpShiftReg;

    ENTER_CRITICAL_SECTION();
    tmpShiftReg = randomst.shiftReg;
    LEAVE_CRITICAL_SECTION();
    endbit = ((tmpShiftReg & 0x8000) != 0)?true:false;
    tmpShiftReg <<= 1;
    if (endbit)
        tmpShiftReg ^= 0x100b;
    tmpShiftReg++;
    ENTER_CRITICAL_SECTION();
    randomst.shiftReg = tmpShiftReg;
    LEAVE_CRITICAL_SECTION();
    tmpShiftReg = tmpShiftReg ^ randomst.mask;
    return tmpShiftReg;
}