added Linear Interpolation (LERP) functions: math.lerp(), floats.lerp(), floats.lerp_fast()

compiler/res/prog8lib/math.p8

@@ -645,4 +645,12 @@ log2_tab
         cx16.r15 ^= $ffff
         cx16.r14 ^= $ffff
     }
+
+
+    sub lerp(ubyte v0, ubyte v1, ubyte t) -> ubyte {
+        ; Linear interpolation (LERP)
+        ; returns an interpolation between two inputs (v0, v1) for a parameter t in the interval [0, 255]
+        ; guarantees v = v1 when t = 255
+        return v0 + msb(t as uword * (v1 - v0) + 255)
+    }
 }

compiler/res/prog8lib/shared_floats_functions.p8

@@ -256,4 +256,18 @@ inline asmsub pop() -> float @FAC1 {
     }}
 }
 
+sub lerp(float v0, float v1, float t) -> float {
+    ; Linear interpolation (LERP)
+    ; Precise method, which guarantees v = v1 when t = 1.
+    ; returns an interpolation between two inputs (v0, v1) for a parameter t in the closed unit interval [0, 1]
+    return (1 - t) * v0 + t * v1
+}
+
+sub lerp_fast(float v0, float v1, float t) -> float {
+    ; Linear interpolation (LERP)
+    ; Imprecise (but slightly faster) method, which does not guarantee v = v1 when t = 1
+    ; returns an interpolation between two inputs (v0, v1) for a parameter t in the closed unit interval [0, 1]
+    return v0 + t * (v1 - v0)
+}
+
 }

compiler/res/prog8lib/virtual/floats.p8

@@ -203,4 +203,18 @@ sub pop() -> float {
     }}
 }
 
+sub lerp(float v0, float v1, float t) -> float {
+    ; Linear interpolation (LERP)
+    ; Precise method, which guarantees v = v1 when t = 1.
+    ; returns an interpolation between two inputs (v0, v1) for a parameter t in the closed unit interval [0, 1]
+    return (1 - t) * v0 + t * v1
+}
+
+sub lerp_fast(float v0, float v1, float t) -> float {
+    ; Linear interpolation (LERP)
+    ; Imprecise (but slightly faster) method, which does not guarantee v = v1 when t = 1
+    ; returns an interpolation between two inputs (v0, v1) for a parameter t in the closed unit interval [0, 1]
+    return v0 + t * (v1 - v0)
+}
+
 }

compiler/res/prog8lib/virtual/math.p8

@@ -398,4 +398,12 @@ math {
         cx16.r15 ^= $ffff
         cx16.r14 ^= $ffff
     }
+
+
+    sub lerp(ubyte v0, ubyte v1, ubyte t) -> ubyte {
+        ; Linear interpolation (LERP)
+        ; returns an interpolation between two inputs (v0, v1) for a parameter t in the interval [0, 255]
+        ; guarantees v = v1 when t = 255
+        return v0 + msb(t as uword * (v1 - v0) + 255)
+    }
 }

docs/source/todo.rst

@@ -5,6 +5,9 @@ replace zsound example by a zsmkit example
 contribute a short how-to to the zsmkit repo for building a suitable blob
 write a howto for integrating third party library code like zsmkit and vtui
 
+can we make it so that math is not always included on 6502 target? (what does it need, move that to another library perhaps?)
+
+
 Improve register load order in subroutine call args assignments:
 in certain situations, the "wrong" order of evaluation of function call arguments is done which results
 in overwriting registers that already got their value, which requires a lot of stack juggling (especially on plain 6502 cpu!)

examples/test.p8

@@ -1,60 +1,20 @@
+%import math
 %import textio
-%import diskio
 %option no_sysinit
 %zeropage basicsafe
 
 main {
 
     sub start() {
-        txt.print_ub(exists_byte("test.prg"))
-        txt.spc()
-        txt.print_ub(exists_byte("doesntexist.xxx"))
-        txt.nl()
-        txt.print_bool(exists_bool("test.prg"))
-        txt.spc()
-        txt.print_bool(exists_bool("doesntexist.xxx"))
-        txt.nl()
-        txt.print_bool(exists1("test.prg"))
-        txt.spc()
-        txt.print_bool(exists1("doesntexist.xxx"))
-        txt.nl()
-        txt.print_bool(exists2("test.prg"))
-        txt.spc()
-        txt.print_bool(exists2("doesntexist.xxx"))
-        txt.nl()
-    }
+        ubyte v1 = 100
+        ubyte v2 = 200
 
-    sub exists1(str filename) -> bool {
-        ; -- returns true if the given file exists on the disk, otherwise false
-        if exists_byte(filename)!=0 {
-            return true
+        for cx16.r0L in 0 to 255 step 16 {
+            txt.print_ub(math.lerp(v1, v2, cx16.r0L))
+            txt.nl()
         }
-        return false
+        txt.print_ub(math.lerp(v1, v2, 255))
+        txt.nl()
     }
 
-    sub exists2(str filename) -> bool {
-        ; -- returns true if the given file exists on the disk, otherwise false
-        if exists_bool(filename) {
-            return true
-        }
-        return false
-    }
-
-
-    sub exists_bool(str name) -> bool {
-        %ir {{
-            loadm.w r65535,main.exists_bool.name
-            syscall 52 (r65535.w): r0.b
-            returnr.b r0
-        }}
-    }
-
-    sub exists_byte(str name) -> ubyte {
-        %ir {{
-            loadm.w r65535,main.exists_byte.name
-            syscall 52 (r65535.w): r0.b
-            returnr.b r0
-        }}
-    }
 }
-