progstart() added to complement progend()

codeGenCpu6502/src/prog8/codegen/cpu6502/ProgramAndVarsGen.kt

@@ -91,6 +91,7 @@ internal class ProgramAndVarsGen(
             OutputType.RAW -> {
                 asmgen.out("; ---- raw assembler program ----")
                 asmgen.out("* = ${options.loadAddress.toHex()}")
+                asmgen.out("prog8_program_start\t; start of program label")
                 asmgen.out("  cld")
                 asmgen.out("  tsx  ; save stackpointer for sys.exit()")
                 asmgen.out("  stx  prog8_lib.orig_stackpointer")
@@ -106,6 +107,7 @@ internal class ProgramAndVarsGen(
                         }
                         asmgen.out("; ---- basic program with sys call ----")
                         asmgen.out("* = ${options.loadAddress.toHex()}")
+                        asmgen.out("prog8_program_start\t; start of program label")
                         val year = LocalDate.now().year
                         asmgen.out("  .word  (+), $year")
                         asmgen.out("  .null  $9e, format(' %d ', prog8_entrypoint), $3a, $8f, ' prog8'")
@@ -122,6 +124,7 @@ internal class ProgramAndVarsGen(
                         // this is the same as RAW
                         asmgen.out("; ---- program without basic sys call ----")
                         asmgen.out("* = ${options.loadAddress.toHex()}")
+                        asmgen.out("prog8_program_start\t; start of program label")
                         asmgen.out("  cld")
                         asmgen.out("  tsx  ; save stackpointer for sys.exit()")
                         asmgen.out("  stx  prog8_lib.orig_stackpointer")
@@ -134,6 +137,7 @@ internal class ProgramAndVarsGen(
             OutputType.XEX -> {
                 asmgen.out("; ---- atari xex program ----")
                 asmgen.out("* = ${options.loadAddress.toHex()}")
+                asmgen.out("prog8_program_start\t; start of program label")
                 asmgen.out("  cld")
                 asmgen.out("  tsx  ; save stackpointer for sys.exit()")
                 asmgen.out("  stx  prog8_lib.orig_stackpointer")

compiler/res/prog8lib/atari/syslib.p8

@@ -336,6 +336,13 @@ save_SCRATCH_ZPWORD2	.word  0
         }}
     }
 
+    inline asmsub progstart() -> uword @AY {
+        %asm {{
+            lda  #<prog8_program_start
+            ldy  #>prog8_program_start
+        }}
+    }
+
     inline asmsub push(ubyte value @A) {
         %asm {{
             pha

compiler/res/prog8lib/c128/syslib.p8

@@ -887,6 +887,13 @@ _no_msb_size
         }}
     }
 
+    inline asmsub progstart() -> uword @AY {
+        %asm {{
+            lda  #<prog8_program_start
+            ldy  #>prog8_program_start
+        }}
+    }
+
     inline asmsub push(ubyte value @A) {
         %asm {{
             pha

compiler/res/prog8lib/c64/syslib.p8

@@ -903,6 +903,13 @@ _no_msb_size
         }}
     }
 
+    inline asmsub progstart() -> uword @AY {
+        %asm {{
+            lda  #<prog8_program_start
+            ldy  #>prog8_program_start
+        }}
+    }
+
     inline asmsub push(ubyte value @A) {
         %asm {{
             pha

compiler/res/prog8lib/cx16/syslib.p8

@@ -1822,6 +1822,13 @@ save_SCRATCH_ZPWORD2	.word  0
         }}
     }
 
+    inline asmsub progstart() -> uword @AY {
+        %asm {{
+            lda  #<prog8_program_start
+            ldy  #>prog8_program_start
+        }}
+    }
+
     inline asmsub push(ubyte value @A) {
         %asm {{
             pha

compiler/res/prog8lib/neo/syslib.p8

@@ -270,6 +270,13 @@ save_SCRATCH_ZPWORD2	.word  0
         }}
     }
 
+    inline asmsub progstart() -> uword @AY {
+        %asm {{
+            lda  #<prog8_program_start
+            ldy  #>prog8_program_start
+        }}
+    }
+
     inline asmsub push(ubyte value @A) {
         %asm {{
             pha

compiler/res/prog8lib/pet32/syslib.p8

@@ -435,6 +435,13 @@ save_SCRATCH_ZPWORD2	.word  0
         }}
     }
 
+    inline asmsub progstart() -> uword @AY {
+        %asm {{
+            lda  #<prog8_program_start
+            ldy  #>prog8_program_start
+        }}
+    }
+
     inline asmsub push(ubyte value @A) {
         %asm {{
             pha

docs/source/libraries.rst

@@ -330,6 +330,11 @@ sys (part of syslib)
     Returns the last address of the program in memory + 1. This means: the memory address directly after all the program code and variables,
     including the uninitialized ones ("BSS" variables) and the uninitialized memory blocks reserved by the `memory()` function.
     Can be used to load dynamic data after the program, instead of hardcoding something.
+    On the assembly level: it returns the address of the symbol "``prog8_program_end``".
+
+``progstart ()``
+    Returns the first address of the program in memory. This usually is $0801 on the C64 and the X16, for example.
+    On the assembly level: it returns the address of the symbol "``prog8_program_start``".
 
 ``wait (uword jiffies)``
     wait approximately the given number of jiffies (1/60th seconds)

examples/test.p8

@@ -1,19 +1,12 @@
-%import math
 %import textio
 %option no_sysinit
 %zeropage basicsafe
 
 main {
     sub start() {
-        uword v0 = 4000
+        txt.print_uwhex(sys.progstart(), true)
-        uword v1 = 60000
+        txt.spc()
-
+        txt.print_uwhex(sys.progend(), true)
-        for cx16.r1 in 65400 to 65535 {
+        txt.nl()
-            txt.print_uw(cx16.r1)
-            txt.spc()
-            txt.spc()
-            txt.print_uw(math.lerpw(v0, v1, cx16.r1))
-            txt.nl()
-        }
     }
 }