fixed optimized code for > and <

codeGenCpu6502/src/prog8/codegen/cpu6502/assignment/AssignmentAsmGen.kt

@@ -1085,6 +1085,7 @@ internal class AssignmentAsmGen(private val program: PtProgram,
         }
     }
 
+    // checked OK:
     private fun byteLess(expr: PtBinaryExpression, signed: Boolean) {
         // note: this is the inverse of byteGreaterEqual
         when(expr.right) {
@@ -1145,8 +1146,12 @@ internal class AssignmentAsmGen(private val program: PtProgram,
                 else
                     asmgen.out("""
                         cmp  P8ZP_SCRATCH_B1
-                        rol  a
+                        bcc  +
-                        and  #1""")
+                        beq  +
+                        lda  #1
+                        bne  ++
++                       lda  #0
++""")
             }
         }
     }
@@ -1155,6 +1160,7 @@ internal class AssignmentAsmGen(private val program: PtProgram,
         // note: this is the inverse of byteGreater
         when(expr.right) {
             is PtNumber -> {
+                // TODO verify if this is correct code on all corner cases
                 val number = (expr.right as PtNumber).number.toInt()
                 asmgen.assignExpressionToRegister(expr.left, RegisterOrPair.A, signed)
                 if(signed)
@@ -1176,6 +1182,7 @@ internal class AssignmentAsmGen(private val program: PtProgram,
                         eor  #1""")
             }
             is PtIdentifier -> {
+                // TODO verify if this is correct code on all corner cases
                 val varname = (expr.right as PtIdentifier).name
                 asmgen.assignExpressionToRegister(expr.left, RegisterOrPair.A, signed)
                 if(signed)
@@ -1197,6 +1204,7 @@ internal class AssignmentAsmGen(private val program: PtProgram,
                         eor  #1""")
             }
             else -> {
+                // TODO verify if this is correct code on all corner cases
                 // note: left and right operands get reversed here to reduce code size
                 asmgen.assignByteOperandsToAAndVar(expr.right, expr.left, "P8ZP_SCRATCH_B1")
                 if(signed)
@@ -1219,6 +1227,7 @@ internal class AssignmentAsmGen(private val program: PtProgram,
         }
     }
 
+    // checked OK:
     private fun byteGreater(expr: PtBinaryExpression, signed: Boolean) {
         // note: this is the inverse of byteLessEqual
         when(expr.right) {
@@ -1229,6 +1238,7 @@ internal class AssignmentAsmGen(private val program: PtProgram,
                     asmgen.out("""
                         sec
                         sbc  #$number
+                        beq  +++
                         bvc  +
                         eor  #$80
 +                       bmi  +
@@ -1239,8 +1249,12 @@ internal class AssignmentAsmGen(private val program: PtProgram,
                 else
                     asmgen.out("""
                         cmp  #$number
-                        lda  #0
+                        bcc  +
-                        rol  a""")
+                        beq  +
+                        lda  #1
+                        bne  ++
++                       lda  #0
++""")
             }
             is PtIdentifier -> {
                 val varname = (expr.right as PtIdentifier).name
@@ -1249,6 +1263,7 @@ internal class AssignmentAsmGen(private val program: PtProgram,
                     asmgen.out("""
                         sec
                         sbc  $varname
+                        beq  +++
                         bvc  +
                         eor  #$80
 +                       bmi  +
@@ -1259,8 +1274,12 @@ internal class AssignmentAsmGen(private val program: PtProgram,
                 else
                     asmgen.out("""
                         cmp  $varname
-                        lda  #0
+                        bcc  +
-                        rol  a""")
+                        beq  +
+                        lda  #1
+                        bne  ++
++                       lda  #0
++""")
             }
             else -> {
                 // note: left and right operands get reversed here to reduce code size
@@ -1290,6 +1309,7 @@ internal class AssignmentAsmGen(private val program: PtProgram,
         // note: this is the inverse of byteLess
         when(expr.right) {
             is PtNumber -> {
+                // TODO verify if this is correct code on all corner cases
                 val number = (expr.right as PtNumber).number.toInt()
                 asmgen.assignExpressionToRegister(expr.left, RegisterOrPair.A, signed)
                 if(signed) {
@@ -1309,6 +1329,7 @@ internal class AssignmentAsmGen(private val program: PtProgram,
                         and  #1""")
             }
             is PtIdentifier -> {
+                // TODO verify if this is correct code on all corner cases
                 val varname = (expr.right as PtIdentifier).name
                 asmgen.assignExpressionToRegister(expr.left, RegisterOrPair.A, signed)
                 if(signed) {
@@ -1328,6 +1349,7 @@ internal class AssignmentAsmGen(private val program: PtProgram,
                         and  #1""")
             }
             else -> {
+                // TODO verify if this is correct code on all corner cases
                 // note: left and right operands get reversed here to reduce code size
                 asmgen.assignByteOperandsToAAndVar(expr.right, expr.left, "P8ZP_SCRATCH_B1")
                 if(signed)

docs/source/todo.rst

@@ -1,8 +1,7 @@
 TODO
 ====
 
-- fix bug introduced by 017ef8a837077c339993004da9b4ccf5c8ca7b13 (> and/or <= change in AssignmentAsmGen byteLessEquals/byteGreater
+- verify all comparison cornercases in the TODOS in AssignmentAsmGen
-  Bug manifests in prog8 where 2nd row of aliens jerks too far to the right after a short while.
 
 - [on branch:] investigate McCarthy evaluation again? this may also reduce code size perhaps for things like if a>4 or a<2 ....
 - IR: reduce the number of branch instructions such as BEQ, BEQR, etc (gradually), replace with CMP(I) + status branch instruction

examples/test.p8

@@ -2,77 +2,153 @@
 %zeropage basicsafe
 
 main {
-    sub start () {
+    sub start() {
-        ubyte[4] @shared array = 10 to 20 step 3
+        greater()
-        ubyte[4] @shared array2 = 20 downto 10 step -3
+        greater_signed()
-        byte[7] @shared array3 = 10 downto -10 step -3
+        less()
-
+        less_signed()
-        ubyte xx
-        byte bb
-
-        cx16.r1=0
-        for cx16.r0 in 0 to 10 {
-            cx16.r1++
-        }
-        txt.print_uw(cx16.r1)
-        txt.nl()
-        txt.nl()
-
-        for xx in array {
-            txt.print_ub(xx)
-            txt.spc()
-        }
-        txt.nl()
-        for xx in array2 {
-            txt.print_ub(xx)
-            txt.spc()
-        }
-        txt.nl()
-        for bb in array3 {
-            txt.print_b(bb)
-            txt.spc()
-        }
-        txt.nl()
-        txt.nl()
-
-
-        for xx in 10 to 20 step 3 {             ; TODO fix IR/VM code that wraps around instead of stopping at 19
-            txt.print_ub(xx)
-            txt.spc()
-        }
-        txt.nl()
-
-        for xx in 20 downto 10 step -3 {        ; TODO fix IR/VM code that wraps around instead of stopping at 11
-            txt.print_ub(xx)
-            txt.spc()
-        }
-        txt.nl()
-
-        for bb in 10 downto -10 step -3 {        ; TODO fix IR/VM code that wraps around instead of stopping at -8
-            txt.print_b(bb)
-            txt.spc()
-        }
-
-        txt.nl()
-        txt.nl()
-        ubyte ending = 20
-
-        for xx in 10 to ending step 3 {
-            txt.print_ub(xx)
-            txt.spc()
-        }
-        txt.nl()
-        ending =10
-        for xx in 20 downto ending step -3 {
-            txt.print_ub(xx)
-            txt.spc()
-        }
-        txt.nl()
-
-        byte endingb = -10
-        for bb in 10 downto endingb step -3 {
-            txt.print_b(bb)
-            txt.spc()
-        }
     }
+
+    sub value(ubyte arg) -> ubyte {
+        cx16.r0++
+        return arg
+    }
+
+    sub svalue(byte arg) -> byte {
+        cx16.r0++
+        return arg
+    }
+
+    sub greater () {
+        ubyte b1 = 10
+        ubyte b2 = 20
+        ubyte b3 = 10
+
+        txt.print("101010: ")
+        ubyte xx
+        xx = b2>10
+        txt.print_ub(xx)
+        txt.spc()
+
+        xx = b2>20
+        txt.print_ub(xx)
+        txt.spc()
+
+        xx = b2>b1
+        txt.print_ub(xx)
+        txt.spc()
+
+        xx = b3>b1
+        txt.print_ub(xx)
+        txt.spc()
+
+        xx = b2>value(10)
+        txt.print_ub(xx)
+        txt.spc()
+        xx = b3>value(20)
+        txt.print_ub(xx)
+        txt.spc()
+
+        txt.nl()
+    }
+
+    sub greater_signed () {
+        byte b1 = -20
+        byte b2 = -10
+        byte b3 = -20
+
+        txt.print("101010: ")
+        ubyte xx
+        xx = b2 > -20
+        txt.print_ub(xx)
+        txt.spc()
+
+        xx = b2 > -10
+        txt.print_ub(xx)
+        txt.spc()
+
+        xx = b2>b1
+        txt.print_ub(xx)
+        txt.spc()
+
+        xx = b3>b1
+        txt.print_ub(xx)
+        txt.spc()
+
+        xx = b2>svalue(-20)
+        txt.print_ub(xx)
+        txt.spc()
+        xx = b3>svalue(-10)
+        txt.print_ub(xx)
+        txt.spc()
+
+        txt.nl()
+    }
+
+    sub less () {
+        ubyte b1 = 20
+        ubyte b2 = 10
+        ubyte b3 = 20
+
+        txt.print("101010: ")
+        ubyte xx
+        xx = b2<20
+        txt.print_ub(xx)
+        txt.spc()
+
+        xx = b2<10
+        txt.print_ub(xx)
+        txt.spc()
+
+        xx = b2<b1
+        txt.print_ub(xx)
+        txt.spc()
+
+        xx = b3<b1
+        txt.print_ub(xx)
+        txt.spc()
+
+        xx = b2<value(20)
+        txt.print_ub(xx)
+        txt.spc()
+        xx = b2<value(10)
+        txt.print_ub(xx)
+        txt.spc()
+
+        txt.nl()
+    }
+
+    sub less_signed () {
+        byte b1 = -10
+        byte b2 = -20
+        byte b3 = -10
+
+        txt.print("101010: ")
+        ubyte xx
+        xx = b2 < -10
+        txt.print_ub(xx)
+        txt.spc()
+
+        xx = b2 < -20
+        txt.print_ub(xx)
+        txt.spc()
+
+        xx = b2<b1
+        txt.print_ub(xx)
+        txt.spc()
+
+        xx = b3<b1
+        txt.print_ub(xx)
+        txt.spc()
+
+        xx = b2<svalue(-10)
+        txt.print_ub(xx)
+        txt.spc()
+        xx = b3<svalue(-20)
+        txt.print_ub(xx)
+        txt.spc()
+
+        txt.nl()
+    }
+
 }