Module Tr_offset

module Tr_offset: sig .. end

Reduction of a location (expressed as an Ival.t and a size) by a base validity. Only the locations in the trimmed result are valid.

type t = private

`\|`	`Invalid`	`(*`	No location is valid	`*)`
`\|`	`Set of Integer.t list`	`(*`	Limited number of locations	`*)`
`\|`	`Interval of Integer.t * Integer.t * Integer.t`
`\|`	`Overlap of Integer.t * Integer.t * Origin.t`	`(*`	The location covers the entire range `min..max`, but consecutive offsets overlap	`*)`

val pretty : t Pretty_utils.formatter

val trim_by_validity : ?origin:Origin.t ->
       Ival.t -> Integer.t -> Base.validity -> bool * t

trim_by_validity ?origin offsets size validity reduces offsets so that all accesses to offsets+(0..size-1) are valid according to validity. The returned boolean indicates that at least one of the offsets does not comply with validity. If the valid offsets cannot be represented precisely, the Imprecise constructor is returned. When specified, the origin argument is used as the source of this imprecision .

This is a more complete specification of this function, for a single offset o. We want to write size>0 bits, on a base possibly valid between min_valid..max_maybe_valid, and guaranteed to be valid between min_valid..max_sure_valid. The case max_sure_valid < min_valid is possible: in this case, no bit is guaranteed to be valid. For Valid and non-Empty bases, min_valid<max_maybe_valid holds. We write start_to==o and stop_to==start_to+size-1. Then

If start_to..stop_to is not included in min_valid..max_maybe_valid, then the write completely fails: at least one bit is outside the validity. This translates to start_to<min_valid || stop_to > max_maybe_valid

If start_to..stop_to is not included in min_valid..max_sure_valid, then we must emit an alarm. This translates to start_to<min_valid || stop_to > max_sure_valid. This convention works even when min_valid..max_sure_valid is not a real interval.