You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: hint.go
    path of file: ./repos/pigo/vendor/github.com/golang/freetype/truetype
    
    the code of the file until where you have to start completion: // Copyright 2012 The Freetype-Go Authors. All rights reserved.
// Use of this source code is governed by your choice of either the
// FreeType License or the GNU General Public License version 2 (or
// any later version), both of which can be found in the LICENSE file.

package truetype

// This file implements a Truetype bytecode interpreter.
// The opcodes are described at https://developer.apple.com/fonts/TTRefMan/RM05/Chap5.html

import (
	"errors"
	"math"

	"golang.org/x/image/math/fixed"
)

const (
	twilightZone = 0
	glyphZone    = 1
	numZone      = 2
)

type pointType uint32

const (
	current      pointType = 0
	unhinted     pointType = 1
	inFontUnits  pointType = 2
	numPointType           = 3
)

// callStackEntry is a bytecode call stack entry.
type callStackEntry struct {
	program   []byte
	pc        int
	loopCount int32
}

// hinter implements bytecode hinting. A hinter can be re-used to hint a series
// of glyphs from a Font.
type hinter struct {
	stack, store []int32

	// functions is a map from function number to bytecode.
	functions map[int32][]byte

	// font and scale are the font and scale last used for this hinter.
	// Changing the font will require running the new font's fpgm
    
func (h *hinter) iupInterp(interpY bool, p1, p2, ref1, ref2 int) {
	if p1 > p2 {
		return
	}
	if ref1 >= len(h.points[glyphZone][current]) ||
		ref2 >= len(h.points[glyphZone][current]) {
		return
	}

	var ifu1, ifu2 fixed.Int26_6
	if interpY {
		ifu1 = h.points[glyphZone][inFontUnits][ref1].Y
		ifu2 = h.points[glyphZone][inFontUnits][ref2].Y
	} else {
		ifu1 = h.points[glyphZone][inFontUnits][ref1].X
		ifu2 = h.points[glyphZone][inFontUnits][ref2].X
	}
	if ifu1 > ifu2 {
		ifu1, ifu2 = ifu2, ifu1
		ref1, ref2 = ref2, ref1
	}

	var unh1, unh2, delta1, delta2 fixed.Int26_6
	if interpY {
		unh1 = h.points[glyphZone][unhinted][ref1].Y
		unh2 = h.points[glyphZone][unhinted][ref2].Y
		delta1 = h.points[glyphZone][current][ref1].Y - unh1
		delta2 = h.points[glyphZone][current][ref2].Y - unh2
	} else {
		unh1 = h.points[glyphZone][unhinted][ref1].X
		unh2 = h.points[glyphZone][unhinted][ref2].X
		delta1 = h.points[glyphZone][current][ref1].X - unh1
		delta2 = h.points[glyphZone][current][ref2].X - unh2
	}

	var xy, ifuXY fixed.Int26_6
	if ifu1 == ifu2 {
		for i := p1; i <= p2; i++ {
			if interpY {
				xy = h.points[glyphZone][unhinted][i].Y
			} else {
				xy = h.points[glyphZone][unhinted][i].X
			}

			if xy <= unh1 {
				xy += delta1
			} else {
				xy += delta2
			}

			if interpY {
				h.points[glyphZone][current][i].Y = xy
			} else {
				h.points[glyphZone][current][i].X = xy
			}
		}
		return
	}

	scale, scaleOK := int64(0), false
	for i := p1; i <= p2; i++ {
		if interpY {
			xy = h.points[glyphZone][unhinted][i].Y
			ifuXY = h.points[glyphZone][inFontUnits][i].Y
		} else {
			xy = h.points[glyphZone][unhinted][i].X
			ifuXY = h.points[glyphZone][inFontUnits][i].X
		}

		if xy <= unh1 {
			xy += delta1
		} else if xy >= unh2 {
			xy += delta2
		} else {
			if !scaleOK {
				scaleOK = true
				scale = mulDiv(int64(unh2+delta2-unh1-delta1), 0x10000, int64(ifu2-ifu1))
			}
			numer := int64(ifuXY-ifu1) * scale
			if numer >= 0 {
				numer += 0x8000
			} else {
				numer -= 0x8000
			}
			xy = unh1 + delta1 + fixed.Int26_6(numer/0x10000)
		}

		if interpY {
			h.points[glyphZone][current][i].Y = xy
		} else {
			h.points[glyphZone][current][i].X = xy
		}
	}
}