view src/vars.s @ 136:e49bd0493baf

Checkpoint updates to immediate mode program editing and some memory handling
author William Astle <lost@l-w.ca>
date Fri, 12 Jul 2024 23:29:45 -0600
parents 917b4893bb3d
children
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                *pragmapush list
                *pragma list
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; Start of memory which has the direct page and other data.
                org 0
dpstart         equ *                           ; start of direct page
zero            rmb 2                           ; constant zero word used for faster zeroing of 16 bit registers
binval          rmb 2                           ; arbitary binary value, usually a line number or integer
memtop          rmb 2                           ; absolute top of memory in 64K memory map
memsize         rmb 2                           ; top of memory not reserved
freetop         rmb 2                           ; top of free memory (bottom of string space)
stringtab       rmb 2                           ; bottom of used string space
cstackptr       rmb 2                           ; bottom of the "stack frame" stack (the actual stack is below here)
prog_linetab    rmb 2                           ; pointer to start of the program line table
prog_linetabp   rmb 2                           ; pointer to the first free program line table entry
prog_text       rmb 2                           ; start of the program text data (immediately after the line table)
vartab          rmb 2                           ; pointer to start of integer scalars (the runtime heap)
objecttab       rmb 2                           ; pointer to start of arrays and other variable sized objects
freestart       rmb 2                           ; pointer to start of unallocated memory
readlinenoecho  rmb 1                           ; if nonzero, the readline routine won't echo its input
console_curptr  rmb 2                           ; current cursor pointer for console driver
console_blnkdel rmb 1                           ; cursor blink delay
console_truelc  rmb 1                           ; set to nonzero if the console supports true lower case (gfx, etc.)
filenum         rmb 1                           ; current input/output channel
fileeof         rmb 1                           ; flag for whether last read detected EOF
keyb_flags      rmb 1                           ; shift flags for the keyboard
keyb_joystate   rmb 1                           ; joystick button state
keyb_repdel     rmb 1                           ; repeat delay
keyb_curscan    rmb 1                           ; current repeating scan code
keyb_buffw      rmb 2                           ; keyboard ring buffer write pointer
keyb_buffr      rmb 2                           ; keyboard ring buffer read pointer
curline         rmb 2                           ; pointer to current line
contline        rmb 2                           ; pointer to line for CONT
contstmt        rmb 2                           ; interpretation pointer for CONT
curstmt         rmb 2                           ; start of statement currently being interpreted
endflag         rmb 1                           ; 00 = END, FF = STOP
stringstackptr  rmb 2                           ; anonymous string descriptor stack pointer
tok_skipkw      rmb 1                           ; flag for when skipping an unrecognized keyword
tok_skipdt      rmb 1                           ; flag for when processing DATA
tok_kwtype      rmb 1                           ; primary/secondary type flag for tokens
tok_kwnum       rmb 1                           ; the actual token number
tok_kwmatchl    rmb 1                           ; the length of the best match during lookup
tok_kwmatch     rmb 2                           ; the current best matched token number
parse_noout     rmb 1                           ; flag for whether we're outputting encoded lines when parsing
parse_tokenst   rmb 2                           ; pointer into input buffer of start of currently parsed token
parse_curtok    rmb 1                           ; current token type code
parse_stackptr  rmb 2                           ; saved stack pointer for bailing out from random parse points
                rmb 0x71-*                      ; align RSTFLG/RSTVEC for stock ROM compatibility
RSTFLG          rmb 1                           ; 0x55 if RSTVEC is valid
RSTVEC          rmb 2                           ; points to warm start routine (must start with NOP)
inputptr        rmb 2                           ; pointer to current program execution location
; General value accumulators used during expression evaluation. These are in the same format used for storing
; values in variables with the exception of having a type flag.
val0            rmb val.size                    ; value accumulator 0 - current expression value
val1            rmb val.size                    ; value accumulator 1 - usually left operand of binary operator
; The fpa0 and fpa1 areas are used for scratch work during floating point operations. They are only used by
; floating point operations and operations related to floating point such as number conversion. This saves a fair
; few clock cycles over simply working off the index register pointers passed into the routines and it also allows
; for being able to leave the input operands for the routines unmodified, or to overlap the input and output
; operands. These floating point accumulators can hold the maximum precision floating point values used by the
; system.
fpa0            rmb fpa.size                    ; floating point accumulator 1
fpa1            rmb fpa.size                    ; floating point accumulator 1
fpaextra        rmb 12                          ; "extra" bytes for calculations
                rmb 0x100-*                     ; make sure the stuff that isn't direct page is outside of it
SW3VEC          rmb 3                           ; SWI3 vector (for compatibility)
SW2VEC          rmb 3                           ; SWI2 vector (for compatibility)
SWIVEC          rmb 3                           ; SWI vector (for compatibility)
NMIVEC          rmb 3                           ; NMI vector (for compatibility)
IRQVEC          rmb 3                           ; IRQ vector (for compatibility)
FRQVEC          rmb 3                           ; FIRQ vector (for compatibility)
keyb_state      rmb 8                           ; rollover table state
keyb_buff       rmb keyb_bufflen                ; the keyboard ring buffer
linebuff        rmb linebuffsize                ; the line input buffer
tokebuff        rmb linebuffsize+50             ; make it as long as line buffer plus a margin
stringstack     rmb 5*stringstacknum            ; reserve space for the anonymous string descriptor stack           
stringstackend  equ *                           ; end of string stack buffer
strbuff         rmb 20                          ; temporary string buffer for converting numbers and other things
                ifne *&0x1ff
                rmb 0x200-(*&0x1ff)
                endc
textscreen      rmb 0x200                       ; the actual text screen (must be on 512 byte alignment)
heapstart       equ *                           ; start of dynamically allocated stuff
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; The heap has the following items in order:
;
; Program text: preceded by a NUL and pointed to by progtext
; Variable table: pointed to by vartab; contains records for all scalar and array variables
; Free space: unused memory between the object table and the stack; pointed to by freestart
; The stack: grows downward from the bottom of string space, pointed to by the stack pointer, obviously
; String space: garbage collected non-constant string data pointed to by freetop
; Reserved memory: immediately above string space; pointed to by memsize
; Actual top of RAM: top of reserved memory; pointed to by memtop
;
; The variable table consists of several symbol tables defined as follows:
;
; Pointer       Size of entry   Variable types
; vartabint     4               Integer scalars
; vartablong    6               Long integer scalars
; vartabfloat   7               Floating point scalars
; vartabstring  6               String scalars
;
; Each entry starts with 2 bytes for the variable name followed by the data payload.
                *pragmapop list