Guru
Joined: 16/09/2019
Location: United KingdomPosts: 3927
| Posted: 11:03am 03 Mar 2022 |
Peter,
I offer this for your consideration regarding manipulating the global data pointer. It's been "mangled" due to the changes I've been making to modularise the MMBasic code for MMB4L, but I'm sure you can figure out how to apply it to your implementation:
/** PEEK(DATAPOS) */
static void peek_datapos(int argc, char **argv, char *p) {
if (argc != 1) ERROR_SYNTAX;
uint64_t data_pos = ((NextDataLine - ProgMemory) << 32) + NextData;
g_integer_rtn = data_pos;
g_rtn_type = T_INT;
}
/** POKE DATAPOS data_pos% */
static void poke_datapos(int argc, char** argv, char *p) {
if (argc != 1) ERROR_ARGUMENT_COUNT;
uint64_t data_pos = (uint64_t) getinteger(p);
NextDataLine = ProgMemory + (data_pos >> 32);
NextData = data_pos & 0xFFFFFFFF;
}
static void peek_datapos(int argc, char **argv, char *p) {
if (argc != 1) ERROR_SYNTAX;
uint64_t data_pos = ((NextDataLine - ProgMemory) << 32) + NextData;
g_integer_rtn = data_pos;
g_rtn_type = T_INT;
}
/** POKE DATAPOS data_pos% */
static void poke_datapos(int argc, char** argv, char *p) {
if (argc != 1) ERROR_ARGUMENT_COUNT;
uint64_t data_pos = (uint64_t) getinteger(p);
NextDataLine = ProgMemory + (data_pos >> 32);
NextData = data_pos & 0xFFFFFFFF;
}
And example MMBasic:
Option Base 0
Option Default None
Option Explicit On
Restore my_data
mad(5)
End
Sub mad(depth%)
If depth% = 0 Then Exit Sub
Local data_pos% = Peek(DataPos) ' Cache the data pointer.
Local s$
Restore my_data
my_label: ' There seems to be an issue with using recursion and DO or FOR loops ?
' Might be MMB4L specific.
Read s$
If s$ = "" Then
Print
Poke DataPos data_pos% ' Restore the data pointer.
Exit Sub
EndIf
Print Space$(5 - depth%) Str$(depth%) s$ " ";
If depth% > 1 Then Print
mad(depth% - 1)
Goto my_label
End Sub
my_data:
Data "A", "B", "C", "D", "E", ""
Option Default None
Option Explicit On
Restore my_data
mad(5)
End
Sub mad(depth%)
If depth% = 0 Then Exit Sub
Local data_pos% = Peek(DataPos) ' Cache the data pointer.
Local s$
Restore my_data
my_label: ' There seems to be an issue with using recursion and DO or FOR loops ?
' Might be MMB4L specific.
Read s$
If s$ = "" Then
Poke DataPos data_pos% ' Restore the data pointer.
Exit Sub
EndIf
Print Space$(5 - depth%) Str$(depth%) s$ " ";
If depth% > 1 Then Print
mad(depth% - 1)
Goto my_label
End Sub
my_data:
Data "A", "B", "C", "D", "E", ""
EDIT: And before anyone starts to "have a go at me" for diverging from "standard" BASIC, we had an extremely flexible way of providing stateless data access by using CSUBs as binary data blobs, until Peter decided it was a hack and wasn't going to be supported by MMB4W
.Edited 2022-03-03 21:18 by thwill