fix a const long value hex asm mistake, fix conv.str_l(0) empty output

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

@@ -870,13 +870,13 @@ class AsmGen6502Internal (
                     when(target.kind) {
                         TargetStorageKind.VARIABLE -> {
                             out("""
-                                lda  #${hex.substring(6,8)}
+                                lda  #$${hex.substring(6,8)}
                                 sta  ${target.asmVarname}
-                                lda  #${hex.substring(4, 6)}
+                                lda  #$${hex.substring(4, 6)}
                                 sta  ${target.asmVarname}+1
-                                lda  #${hex.substring(2, 4)}
+                                lda  #$${hex.substring(2, 4)}
                                 sta  ${target.asmVarname}+2
-                                lda  #${hex.take(2)}
+                                lda  #$${hex.take(2)}
                                 sta  ${target.asmVarname}+3""")
                         }
                         TargetStorageKind.ARRAY -> TODO("assign long to array  ${target.position}")

compiler/res/prog8lib/conv.p8

@@ -269,6 +269,10 @@ sub  str_l  (long value) -> str  {
             bne  +
             inx
             bne  -
++           cpx  #10   ; just all 0? keep one
+            bne  +
+            dex
+
 +           ; x points at the rightmost leading 0
             lda  negative
             beq  +

docs/source/todo.rst

@@ -1,6 +1,8 @@
 TODO
 ====
 
+fix crash for  txt.print_l(conv.str_l(0))
+
 
 STRUCTS and TYPED POINTERS
 --------------------------

examples/test.p8

@@ -3,12 +3,17 @@
 
 main {
     sub start() {
-        long lv1, lv2, lv3
+        txt.print_l(0)
-
+        txt.nl()
-        lv1 = 999999
+        txt.print(conv.str_l(0))
-        lv2 = 555555
+;        long lv1, lv2, lv3
-        lv3 = 222222
+;
-        lv1 = lv2-(lv3*2)
+;        lv1 = 999999
-        txt.print_l(lv1)
+;        lv2 = 555555
+;        lv3 = 222222
+;        lv1 = lv2-(lv3 | $2222)
+;        txt.print_l(lv1)
+;        txt.spc()
+;        txt.print_ulhex(lv1, true)
     }
 }