+/* This program operates by filling in a state table representing the best
+ * possible trips you could make; the ones that makes you the most money.
+ * This is feasible because we don't look at all the possible trips.
+ * We define a list of things that are germane to this game and then only
+ * consider the best outcome in each possible game state.
+ *
+ * Each cell in the table represents a state in the game. In each cell,
+ * we track two things: 1. the most money you could possibly have while in
+ * that state and 2. one possible way to get into that state with that
+ * amount of money.
+ *
+ * A basic analysis can be done with a two-dimensional table: location and
+ * fuel. planeteer-1.0 used this two-dimensional table. This version
+ * adds features mostly by adding dimensions to this table.
+ *
+ * Note that the sizes of each dimension are data driven. Many dimensions
+ * collapse to one possible value (ie, disappear) if the corresponding
+ * feature is not enabled.
+ *
+ * The order of the dimensions in the list of constants below determines
+ * their layout in RAM. The cargo-based 'dimensions' are not completely
+ * independent -- some combinations are illegal and not used. They are
+ * handled as three dimensions rather than one for simplicity. Placing
+ * these dimensions first causes the unused cells in the table to be
+ * grouped together in large blocks. This keeps them from polluting
+ * cache lines, and if they are large enough, allows the memory manager
+ * to swap out entire pages.
+ *
+ * If the table gets too big to fit in RAM:
+ * * Combine the Edens, Cloaks, and UnusedCargo dimensions. Of the
+ * 24 combinations, only 15 are legal: a 38% savings.
+ * * Reduce the size of the Fuel dimension to 3. We only ever look
+ * backwards 2 units, so just rotate the logical values through
+ * the same 3 physical addresses. This is good for an 82% savings.
+ * * Reduce the size of the Edens dimension from 3 to 2, for the
+ * same reasons as Fuel above. 33% savings.
+ * * Buy more ram. (Just sayin'. It's cheaper than you think.)
+ *
+ */
+
+// The official list of dimensions:
+const (
+ // Name Num Size Description
+ Edens = iota // 1 3 # of Eden warp units (0 - 2 typically)
+ Cloaks // 2 1-2 # of Devices of Cloaking (0 or 1)
+ UnusedCargo // 3 4 # of unused cargo spaces (0 - 3 typically)
+ Fuel // 4 17 Hyper jump power left (0 - 16)
+ Location // 5 26 Location (which planet)
+ Hold // 6 15 Cargo bay contents (a *Commodity or nil)
+ Traded // 7 2 Traded yet?
+ BuyFighters // 8 1-2 Errand: Buy fighter drones
+ BuyShields // 9 1-2 Errand: Buy shield batteries
+ Visit // 10 1-2**N Visit: Stop by these N planets in the route
+
+ NumDimensions
+)
+
+func bint(b bool) int {
+ if b {
+ return 1
+ }
+ return 0
+}
+
+func DimensionSizes(data planet_data) []int {
+ eden_capacity := data.Commodities["Eden Warp Units"].Limit
+ if *start_edens > eden_capacity {
+ eden_capacity = *start_edens
+ }
+ cloak_capacity := bint(*cloak)
+ dims := make([]int, NumDimensions)
+ dims[Edens] = eden_capacity + 1
+ dims[Cloaks] = cloak_capacity + 1
+ dims[UnusedCargo] = eden_capacity + cloak_capacity + 1
+ dims[Fuel] = *fuel + 1
+ dims[Location] = len(data.Planets)
+ dims[Hold] = len(data.Commodities) + 1
+ dims[Traded] = 2
+ dims[BuyFighters] = bint(*drones > 0) + 1
+ dims[BuyShields] = bint(*batteries > 0) + 1
+ dims[Visit] = 1 << uint(len(visit()))
+
+ // Remind myself to add a line above when adding new dimensions
+ for i, dim := range dims {
+ if dim < 1 {
+ panic(i)
+ }
+ }
+ return dims
+}
+
+func StateTableSize(dims []int) int {
+ product := 1
+ for _, size := range dims {
+ product *= size
+ }
+ return product
+}
+
+type State struct {
+ value, from int32
+}
+
+const (
+ FROM_ROOT = -2147483647 + iota
+ FROM_UNINITIALIZED
+ VALUE_UNINITIALIZED
+ VALUE_BEING_EVALUATED
+ VALUE_RUBISH
+)
+
+func EncodeIndex(dims, addr []int) int32 {
+ index := addr[0]
+ if addr[0] > dims[0] {
+ panic(0)
+ }
+ for i := 1; i < NumDimensions; i++ {
+ if addr[i] < 0 || addr[i] >= dims[i] {
+ panic(i)
+ }
+ index = index*dims[i] + addr[i]
+ }
+ return int32(index)
+}
+
+func DecodeIndex(dims []int, index int32) []int {
+ addr := make([]int, NumDimensions)
+ for i := NumDimensions - 1; i > 0; i-- {
+ addr[i] = int(index) % dims[i]
+ index /= int32(dims[i])
+ }
+ addr[0] = int(index)
+ return addr
+}
+
+func CreateStateTable(data planet_data, dims []int) []State {
+ table := make([]State, StateTableSize(dims))
+ for i := range table {
+ table[i].value = VALUE_UNINITIALIZED
+ table[i].from = FROM_UNINITIALIZED
+ }
+
+ addr := make([]int, NumDimensions)
+ addr[Fuel] = *fuel
+ addr[Edens] = *start_edens
+ addr[Location] = data.p2i[*start]
+ addr[Traded] = 1
+ start_index := EncodeIndex(dims, addr)
+ table[start_index].value = int32(*funds)
+ table[start_index].from = FROM_ROOT
+
+ return table
+}
+
+/* CellValue fills in the one cell at address addr by looking at all
+ * the possible ways to reach this cell and selecting the best one. */
+
+func Consider(data planet_data, dims []int, table []State, there []int, value_difference int, best_value *int32, best_source []int) {
+ there_value := CellValue(data, dims, table, there)
+ if value_difference < 0 && int32(-value_difference) > there_value {
+ /* Can't afford this transition */
+ return
+ }
+ possible_value := there_value + int32(value_difference)
+ if possible_value > *best_value {
+ *best_value = possible_value
+ copy(best_source, there)
+ }
+}
+
+var cell_filled_count int
+
+func CellValue(data planet_data, dims []int, table []State, addr []int) int32 {
+ my_index := EncodeIndex(dims, addr)
+ if table[my_index].value == VALUE_BEING_EVALUATED {
+ panic("Circular dependency")
+ }
+ if table[my_index].value != VALUE_UNINITIALIZED {
+ return table[my_index].value
+ }
+ table[my_index].value = VALUE_BEING_EVALUATED
+
+ best_value := int32(VALUE_RUBISH)
+ best_source := make([]int, NumDimensions)
+ other := make([]int, NumDimensions)
+ copy(other, addr)
+ planet := data.i2p[addr[Location]]
+
+ /* Travel here */
+ if addr[Traded] == 0 { /* Can't have traded immediately after traveling. */
+ other[Traded] = 1 /* Travel from states that have done trading. */
+
+ /* Travel here via a 2-fuel unit jump */
+ if addr[Fuel]+2 < dims[Fuel] {
+ other[Fuel] = addr[Fuel] + 2
+ hole_index := (dims[Fuel] - 1) - (addr[Fuel] + 2)
+ if hole_index >= len(flight_plan()) || addr[Location] != data.p2i[flight_plan()[hole_index]] {
+ for other[Location] = 0; other[Location] < dims[Location]; other[Location]++ {
+ if data.Planets[data.i2p[addr[Location]]].BeaconOn {
+ Consider(data, dims, table, other, 0, &best_value, best_source)
+ }
+ }
+ }
+ other[Location] = addr[Location]
+ other[Fuel] = addr[Fuel]
+ }
+
+ /* Travel here via a 1-fuel unit jump (a hyper hole) */
+ if addr[Fuel]+1 < dims[Fuel] {
+ hole_index := (dims[Fuel] - 1) - (addr[Fuel] + 1)
+ if hole_index < len(flight_plan()) && addr[Location] == data.p2i[flight_plan()[hole_index]] {
+ other[Fuel] = addr[Fuel] + 1
+ for other[Location] = 0; other[Location] < dims[Location]; other[Location]++ {
+ Consider(data, dims, table, other, 0, &best_value, best_source)
+ }
+ other[Location] = addr[Location]
+ other[Fuel] = addr[Fuel]
+ }
+ }
+
+ /* Travel here via Eden Warp Unit */
+ if addr[Edens]+1 < dims[Edens] && addr[UnusedCargo] > 0 {
+ _, available := data.Planets[data.i2p[addr[Location]]].RelativePrices["Eden Warp Units"]
+ if !available {
+ other[Edens] = addr[Edens] + 1
+ if other[Hold] != 0 {
+ other[UnusedCargo] = addr[UnusedCargo] - 1
+ }
+ for other[Location] = 0; other[Location] < dims[Location]; other[Location]++ {
+ Consider(data, dims, table, other, 0, &best_value, best_source)
+ }
+ other[Location] = addr[Location]
+ other[UnusedCargo] = addr[UnusedCargo]
+ other[Edens] = addr[Edens]
+ }
+ }
+ other[Traded] = addr[Traded]
projects / planeteer / blobdiff