Start using named types: PhysicalIndex

[planeteer] / planeteer.go

diff --git a/planeteer.go b/planeteer.go
index d81713eb9e9073e077617d9ff7dc710ac9da4502..7c5b2e77e414bd57f3d4d8b4894e4129429d1fb8 100644 (file)
--- a/planeteer.go
+++ b/planeteer.go
@@ -170,16 +170,18 @@ func ReadData() (data planet_data) {
  * 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.
+ * grouped together in large blocks.  This keeps the unused cells from
+ * polluting cache lines, and if the spans of unused cells 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 Fuel dimension to 3.  Explicit iteration
+ *      only ever needs to look backwards 2 units, so the logical values
+ *      can rotate through the same 3 physical addresses.  This would be
+ *      good for an 82% savings.  Note that explicit iteration went away
+ *      in 0372f045.
  *    * 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.)
@@ -246,7 +248,8 @@ func StateTableSize(dims []int) int {
 }
 
 type State struct {
-       value, from int32
+       value int32
+       from  PhysicalIndex
 }
 
 const (
@@ -257,7 +260,9 @@ const (
        VALUE_RUBISH
 )
 
-func EncodeIndex(dims, addr []int) int32 {
+type PhysicalIndex int32
+
+func EncodeIndex(dims, addr []int) PhysicalIndex {
        index := addr[0]
        if addr[0] > dims[0] {
                panic(0)
@@ -268,16 +273,17 @@ func EncodeIndex(dims, addr []int) int32 {
                }
                index = index*dims[i] + addr[i]
        }
-       return int32(index)
+       return PhysicalIndex(index)
 }
 
-func DecodeIndex(dims []int, index int32) []int {
+func DecodeIndex(dims []int, index PhysicalIndex) []int {
+       scratch := int(index)
        addr := make([]int, NumDimensions)
        for i := NumDimensions - 1; i > 0; i-- {
-               addr[i] = int(index) % dims[i]
-               index /= int32(dims[i])
+               addr[i] = scratch % dims[i]
+               scratch /= dims[i]
        }
-       addr[0] = int(index)
+       addr[0] = scratch
        return addr
 }
 
@@ -551,8 +557,8 @@ func FinalState(dims []int) []int {
        return addr
 }
 
-func FindBestState(data planet_data, dims []int, table []State, addr []int) int32 {
-       max_index := int32(-1)
+func FindBestState(data planet_data, dims []int, table []State, addr []int) PhysicalIndex {
+       max_index := PhysicalIndex(-1)
        max_value := 0.0
        max_fuel := 1
        if *fuel == 0 {
@@ -591,7 +597,7 @@ func Commas(n int32) (s string) {
        return
 }
 
-func FighterAndShieldCost(data planet_data, dims []int, table []State, best int32) {
+func FighterAndShieldCost(data planet_data, dims []int, table []State, best PhysicalIndex) {
        if *drones == 0 && *batteries == 0 {
                return
        }
@@ -612,7 +618,7 @@ func FighterAndShieldCost(data planet_data, dims []int, table []State, best int3
        }
 }
 
-func EndEdensCost(data planet_data, dims []int, table []State, best int32) {
+func EndEdensCost(data planet_data, dims []int, table []State, best PhysicalIndex) {
        if *end_edens == 0 {
                return
        }
@@ -628,7 +634,7 @@ func EndEdensCost(data planet_data, dims []int, table []State, best int32) {
        }
 }
 
-func VisitCost(data planet_data, dims []int, table []State, best int32) {
+func VisitCost(data planet_data, dims []int, table []State, best PhysicalIndex) {
        if dims[Visit] == 1 {
                return
        }
@@ -643,7 +649,7 @@ func VisitCost(data planet_data, dims []int, table []State, best int32) {
        }
 }
 
-func EndLocationCost(data planet_data, dims []int, table []State, best int32) {
+func EndLocationCost(data planet_data, dims []int, table []State, best PhysicalIndex) {
        if len(end()) == 0 {
                return
        }
@@ -658,7 +664,7 @@ func EndLocationCost(data planet_data, dims []int, table []State, best int32) {
        *end_string = save_end_string
 }
 
-func DescribePath(data planet_data, dims []int, table []State, start int32) (description []string) {
+func DescribePath(data planet_data, dims []int, table []State, start PhysicalIndex) (description []string) {
        for index := start; table[index].from > FROM_ROOT; index = table[index].from {
                if table[index].from == FROM_UNINITIALIZED {
                        panic(index)