69 lines
1.9 KiB
Go
69 lines
1.9 KiB
Go
package modbus
|
|
|
|
import "sort"
|
|
|
|
type request struct {
|
|
address uint16
|
|
length uint16
|
|
fields []field
|
|
tags map[string]string
|
|
}
|
|
|
|
func newRequest(f field, tags map[string]string) request {
|
|
r := request{
|
|
address: f.address,
|
|
length: f.length,
|
|
fields: []field{f},
|
|
tags: map[string]string{},
|
|
}
|
|
|
|
// Copy the tags
|
|
for k, v := range tags {
|
|
r.tags[k] = v
|
|
}
|
|
return r
|
|
}
|
|
|
|
func groupFieldsToRequests(fields []field, tags map[string]string, maxBatchSize uint16) []request {
|
|
if len(fields) == 0 {
|
|
return nil
|
|
}
|
|
|
|
// Sort the fields by address (ascending) and length
|
|
sort.Slice(fields, func(i, j int) bool {
|
|
addrI := fields[i].address
|
|
addrJ := fields[j].address
|
|
return addrI < addrJ || (addrI == addrJ && fields[i].length > fields[j].length)
|
|
})
|
|
|
|
// Construct the consecutive register chunks for the addresses and construct Modbus requests.
|
|
// For field addresses like [1, 2, 3, 5, 6, 10, 11, 12, 14] we should construct the following
|
|
// requests (1, 3) , (5, 2) , (10, 3), (14 , 1). Furthermore, we should respect field boundaries
|
|
// and the given maximum chunk sizes.
|
|
var requests []request
|
|
|
|
current := newRequest(fields[0], tags)
|
|
for _, f := range fields[1:] {
|
|
// Check if we need to interrupt the current chunk and require a new one
|
|
needInterrupt := f.address != current.address+current.length // not consecutive
|
|
needInterrupt = needInterrupt || f.length+current.length > maxBatchSize // too large
|
|
|
|
if !needInterrupt {
|
|
// Still safe to add the field to the current request
|
|
current.length += f.length
|
|
if !f.omit {
|
|
// Omit adding the field but use it for constructing the request.
|
|
current.fields = append(current.fields, f)
|
|
}
|
|
continue
|
|
}
|
|
|
|
// Finish the current request, add it to the list and construct a new one
|
|
requests = append(requests, current)
|
|
current = newRequest(f, tags)
|
|
}
|
|
requests = append(requests, current)
|
|
|
|
return requests
|
|
}
|