Method for obtaining soft information of LDPC code for NAND flash

The invention discloses a method for obtaining soft information of an LDPC code for NAND flash. According to the method, firstly, K times of hard reading and K times of hard decoding are carried out in a threshold voltage changing mode, wherein K is a positive integer; if one time of hard decoding succeeds, return of decoding succeeds; and if K times of hard decoding do not succeed, soft information is generated according to results of the K times of hard reading, and soft decoding is carried out. According to the method, the requirement for multiple times of NAND reading during soft decisioncan be reduced, occupation of memory resources, NAND reading resources and rear-end transmission bandwidth resources is reduced, and delay time is shortened. 本发明公开一种获得NAND闪存LDPC码软信息的方法，本方法首先采用更改阈值电压的方式进行K次硬读取、K次硬解码，K为正整数，若K次硬解码中有一次成功，则返回解码成功，若K次硬解码均不成功，则根据K次硬读取结果生成软信息，进行软解码。本发明能够减少软判决时的多次NAND读取需求，降低了内存资源、NAND读取资源和后端传输带宽资源的占用，减少了延时时间。