Multi-phased programming with balanced gray coding

A method implemented using one or more controllers for one or more storage devices, the method comprising:

• programming, in a first phase, a first portion of data into memory cells of a flash memory in a first-level cell mode;
• retaining, in a cache comprising single-level cells (SLC), at least a subset of the data;
• regenerating the data from at least the cache, wherein the regenerated data includes a second portion of the data;
• and
• programming, in a second phase, the regenerated data in a second-level cell mode based on a mapping from the first-level cell mode to the second-level cell mode,
• wherein the mapping maps each state distribution in the first-level cell mode to at least two non-adjacent state distributions in the second-level cell mode, and
• wherein the mapping provides a width of each state distribution in the first-level cell mode that is less than a combined width of corresponding state distributions in the second-level cell mode.

A system, comprising:

• means for programming, in a first phase, a first portion of data into memory cells of a flash memory in a multi-level cell (MLC) mode;
• means for retaining, in a cache comprising single-level cells (SLC), at least a subset of the data;
• means for regenerating the data from at least the cache, wherein the regenerated data includes a second portion of the data;
• and
• means for programming, in a second phase, the regenerated data in a quad-level cell (QLC) mode based on a mapping from the MLC mode to the QLC mode,
• wherein the mapping maps each state distribution in the MLC mode to at least two non-adjacent state distributions in the QLC mode, and
• wherein the mapping is configured so that a width of each state distribution in the MLC mode is less than a combined width of corresponding state distributions in the QLC mode, and wherein the mapping is configured to provide a balanced Gray code in the MLC mode and the QLC mode.