//[of]:description
//[c]Utility functions to copy, compare memory blocks
//[cf]
//[of]:imports
//[c]
import "base/types"
import "c-types"
//[cf]
//[of]:types
//[c]
typedef bytes = [] byte
typedef dwords = [] dword
typedef chars = [] char
//[cf]
//[c]
//[of]:copy (dst, src, size)
//[c]Copies a memory block
//[c]
public func copy (dst: mem, src: mem, size: size)
	
	def p = src:bytes
	def q = dst:bytes
	def limit = q + size

	// Optimize for big memory blocks
	if size>64
	
		// Align destination on a long word
		while is not aligned (q, 3, 0)
			q++[] = p++[]
		end

		// Copy long words
		limit -= 3
		def pd = p:dwords
		def qd = q:dwords
		while qd<limit
			qd++[] = pd++[]
		end
		limit += 3
		p = pd:bytes
		q = qd:bytes
		
	end
	
	while q<>limit
		q++[] = p++[]
	end

end
//[cf]
//[of]:move (dst, src, size)
//[c]Moves a memory block
//[c]
public func move (dst: mem, src: mem, size: size)

	equ s = src:bytes
	equ d = dst:bytes
	
	if d == s
		return
	end
	
	// incremental copy if dst is after src or 
	// if dst is after the end of src
	if d < s || s+size <= d
		copy (d, s, size)
	else
		def q = d + size
		def p = s + size
		while q<>d
			(--q)[] = (--p)[]
		end
	end

end		
//[cf]
//[of]:first occurrence (buf, char, size)
//[c]Returns the first occurrence of a char
//[c]
public func first occurrence (buf: mem, c: char, size: size)

	def p = buf:chars
	def limit = p + size
	while p<limit
		if p[]==c
			return p
		end
		++p
	end

	return nil	
end
//[cf]
//[of]:compare (dst, src, size)
//[c]Compare two memory blocks
//[c]
public func compare (dst: mem, src: mem, size: size)

	def p = src:bytes
	def q = dst:bytes
	def limit = q + size
	
	while q < limit
		def diff = q[] - p[]
		if diff <> 0:byte
			// extend with sign
			return diff:octet:int
		end
		++p
		++q
	end
	
	return 0
end
//[cf]
//[c]
//[of]:is equal (dst, src, size)
//[c]
public equ is equal (dst: mem, src: mem, size: size) = 

	compare (dst, src, size) == 0

//[cf]
//[of]:not equal (dst, src, size)
//[c]
public equ not equal (dst: mem, src: mem, size: size) = 

	compare (dst, src, size) <> 0

//[cf]