STM8L151F2 power management

[AG1]

Hi trying to reduce the current consumption in STM8L151F2 series controller in HALT mode

but unable to achieve the 0.4uA current rating as mentioned in datasheet,

also want to make the automatically shift the MCU on HSC, but it is not happening, as my external source can give clock of 2MHz for 10ms & goes for sleep itself for remaining 1sec

please find the attached source code for the same

let me know , if any one having solution on the same