Commit: ceaa83536f598f3acf6f1870a131adc21a6c8eda - fig_sh (git)

Implementing figFORTH on SH3 assembler

Commit MetaInfo

• Revisión: ceaa83536f598f3acf6f1870a131adc21a6c8eda (tree)
• Tiempo: 2014-03-13 19:27:33
• Autor: Joel Matthew Rees <reiisi@user...>
• Commiter: Joel Matthew Rees

Log Message

Mostly work on the memory map, getting the various allocation regions defined and bounded for testing.

Cambiar Resumen

• modified: context.inc
• modified: evaluator.inc
• modified: initialize.inc
• modified: inout.inc
• modified: main.src
• modified: teststuff.inc

Diferencia incremental

--- a/context.inc
+++ b/context.inc
@@ -33,8 +33,12 @@
 
 	.cpu	sh3
 
-; For huge things, like U/ (USLASH) might be cut in half and repeated or something.
-PRIORITY_SIZE:	.DEFINE	"1"
+; For huge things, like U/ (USLASH),
+; which might be cut in half and repeated or something. But probably not.
+; PRIORITY_SIZE:	.DEFINE	"1"
+
+; Uncomment this if building for ROM:
+; BUILD_FOR_ROM:		.DEFINE	"1"
 
 ; Comment this out when all forward references are resolved,
 ; and test stuff is no longer needed.
@@ -94,13 +98,26 @@ BYTE_hHI_bHI:	.equ	MSBYTEinNAT
 ; ******************************************************************************
 
 
+; ******************************************************************************
+; Setting up the overall memory map:
+;
 ; The SH-3 has modern dev tools, so we don't have to pay much attention 
-; to memory layout,
-; but we do want to keep the following virtual map in mind:
-
+; to memory layout.
+;
+; But we do need a map to work with.
+;
+; By tradition, the start of object code contained jumps to the initialization code:
+; COLD entry point (4 byte jump) and
+; WARM entry point (4 byte jump), followed by the
+; Init constants table (about 20 natural-width entries).
+;
+; The init constants would be followed by the dictionary, 
+; usually starting with the inner interpreter, 
+; and proceeding to higher-level stuff:
+;
 ; ------------
 ; low address:
-; JMP to start (But, no. Handled through the reset code.)
+; JMP to start (But maybe handled through the reset code?)
 ; 
 ; Global constants table
 ;
@@ -118,7 +135,116 @@ BYTE_hHI_bHI:	.equ	MSBYTEinNAT
 ; 
 ; high address of ROMmable part
 ; -----------------------------
+;
+; If the object were ROMmable, at the end of the object code (ROM image)
+; there would be a non-linked definition of "FORTH"
+; to be copied to RAM, and the RAM part of the dictionary would link to that.
+;
+; In modern processors, ROM can be placed above or below RAM, 
+; so we shouldn't concern ourselves too much about where it is
+; (or even what the map looks like within it).
+;
+; What concerns us is the RAM map, which is traditionally not well defined.
+;
+; These are the large areas of memory which we need to specify allocation for:
+; 
+; ------------------------------------------------------------------------------
+; Prebuilt dictionary (potentially ROMmable).
+; 
+; Run-time dictionary (starts with the "FORTH" entry).
+;    The un-allocated area of the run-time dictionary 
+;    is used as a general purpose text buffer.
+;
+; Parameter stack.
+;    fig-FORTH had this growing down towards the dictionary, 
+;    which we now know is an invitation for attacks.
+;
+; Terminal line input buffer.
+;
+; Return, or flow-of-control stack.
+;    fig-FORTH had this growing down toward the input buffer, 
+;    which, again, we now know is a recipe for vulnerabilities.
+;
+; Per-USER variable table(s).
+;
+; Disk buffers.
+; 
+; ******************************************************************************
+; The 6800 model modified the map to match customary memory use on the 6800:
+;
+; The bottom 128 bytes or so of memory in a 6800 were generally RAM, 
+; because of the direct-page fast-addressing mode. 
+; (ROM at the bottom might have made more sense, 
+; to deal with small integers mistakenly used as pointers.)
+;
+; From 0x80 to 0xff was also in the direct page range, 
+; but might be ROM, for fast access to constants. 
+; (And, beginning with the 6801, IIRC, heavily used routines.)
+;
+; From 0x100 to 0x1000 might not be populated, or might have RAM.
+;
+; The very top of memory, 0xF000 to 0xFFFF, was often populated 
+; with a monitor (debug/BIOS) ROM, to allow the reset and interupt vectors 
+; to be easily read out of ROM.
+;
+; The 6800 fig-FORTH model used the following map:
+;
+; ------------------------------------------------------------------------------
+;
+; 0x00E0: Scratch pad RAM (substitute for CPU temporary registers).
+; 0x00F0: The virtual machine registers (IP, SP, RP, W).
+;         ...
+; 0x0100: Run-time dictionary
+;         ...
+;         Parameter stack
+; 0x0F30: Terminal input buffer
+;         ...
+;         Return stack
+; 0x1000: Pre-built (ROMmable) dictionary
+;    Including COLD and WARM entry jumps and initialization table at the front.
+;         ...
+; 0x3000: disk buffers (4*128)
+;         ...
+; 0x3210: RAM disk (very small)
+;         ...
+; 0x3FFF: End of RAM
+;
+; So, ....
+;
+; ******************************************************************************
+; Some general limits to build within:
+
+; Small while debugging, so we don't have to hunt too far.
+RUNTIME_DICTIONARY_SIZE:	.equ	h'1000	
+
+; Small while debugging, so we don't have to hunt too far.
+PARAMETER_STACK_SIZE:	.equ h'60	
 
+; Keep it small while debugging.
+CONTROL_STACK_SIZE:	.equ	h'60	
+
+; Something to help avoid things bumping into things.
+ALLOC_GAP:	.equ	h'10	
+
+; This can be bigger later.
+TERMINAL_INPUT_BUFFER_SIZE:	.equ	h'100
+
+; Well, maybe we'll get this far some day.
+N_USERS:	.equ 8	
+
+; This can be bigger later, too.
+DISK_BUFFER_SIZE:	.equ	h'100
+DISK_BUFFER_RECORD_SIZE:	.equ	2*NATURAL_SIZE+DISK_BUFFER_SIZE
+DISK_BUFFER_COUNT:	.equ	4
+
+; RAM disk could be useful 
+; even after the full system is running with real (flash?) disks.
+; So could a "ROM" disk with initial error messages. Maybe. Hmm. Anyway.
+RAM_DISK_SIZE:	.equ	h'8000
+
+
+; ******************************************************************************
+; Mapping the virtual machine registers:
 
 ; r0 must be used for many intermediate values.
 ; r0 -- r7 are bank-switched on interrupt.
@@ -146,11 +272,12 @@ fIP:	.reg	r5	; virtual Instruction Pointer
 ; Defined symbols (objects/routines) are called "WORDs" in classic FORTH.
 fW:		.reg	r4	; currently executing Word definition pointer
 ;
-; By keeping the FORTH model in registers
-; that the SH3 bank-switches out during interrupts, 
+; By keeping the FORTH model in banked registers 
+; that the SH3 switches out during interrupts, 
 ; we can save a lot of time during interrupt processing.
 
 
+; ******************************************************************************
 ; Structure of the per-USER variables table:
 	.section usertable, dummy
 	.org	0
@@ -215,7 +342,6 @@ IOSTAT:	.equ $-UORIG
 UTABLESZ:	.equ $-UORIG
 
 
-
 ; Structure of the symbol table entry:
 ; Length byte of the symbol name (NFA)
 ; 	high bit set to flag the start byte

--- a/evaluator.inc
+++ b/evaluator.inc
@@ -500,6 +500,22 @@ myTOGGLE:	.DEFINE "1"
 	HIHEADER	PTRWIDTH, PTRWIDTH, DOCON
 	.data.l	NATURAL_SIZE
 
+; These should be linear arrays, but there is no linear array in fig-FORTH model.
+; NBYTEORDER  ( --- u )
+;           Offsets of bytes in natural word, high byte is byte 0.
+;           Access as byte array of length NWIDTH.
+;           Not part of the fig-FORTH model, should have been.
+;	HIHEADER	NBYTEORDER, NBYTEORDER, DOCON
+;	.data.l	h'00010203
+;
+; PBYTEORDER  ( --- u )
+;           Offsets of bytes in address/pointer, high byte is byte 0.
+;           Access as byte array of length PTRWIDTH.
+;           Not part of the fig-FORTH model, should have been.
+;	HIHEADER	PBYTEORDER, PBYTEORDER, DOCON
+;	.data.l	h'00010203
+; But we can define them high-level, so hold them off until we need them.
+
 ; BL      ( --- u )
 	HIHEADER	BL, BL, DOCON
 	.data.l	" "	; ascii blank

--- a/initialize.inc
+++ b/initialize.inc
@@ -39,7 +39,7 @@
 
 	HEADER	COLD, CENT
 ; WENT will also move, eventually.
-WENT:
+_fWENT:
 	mov.l	#PER_USER, fUP
 ;
 ; Eventually want to initialize these from the COLD_PARAMETERS table --

--- a/inout.inc
+++ b/inout.inc
@@ -116,3 +116,46 @@
 
 
 
+; FIRST  ( --- adr )     The base of the disk buffer space.
+;        Returns the address of the lowest disk block buffer.
+;
+	HIHEADER	FIRST, FIRST, DOCON
+	.data.l	DISK_BUFFERS
+
+
+; LIMIT  ( --- adr )     The limit of the disk buffer space.
+;        Returns the address one beyond the highest disk block buffer.
+;        In many fig FORTHs, this would mark the end of system memory.
+;        Not so in this SH-3 implementation.
+;
+	HIHEADER	LIMIT, LIMIT, DOCON
+	.data.l	DISK_BUFFERS_END
+
+
+; B/BUF  ( --- size )     The size, in bytes, of a buffer.
+;        Bytes per buffer, or the size of a disk block.
+;
+	HIHEADER	"B/BUF", BBUF, DOCON
+	.data.l	DISK_BUFFER_SIZE
+
+
+
+
+; B/SCR  ( --- count )       The size, in buffers, of a screen.
+;        Blocks per screen. 
+;        A screen is the traditional unit of disk space in the old FORTH.
+;
+;        It's a good rule-of-thumb limit on the size of a word definition,
+;        named for the size of a useable small screen --
+;        16 lines, 64 columns in 20x80.
+;
+;        Many traditional FORTH text editors organized the screen this way.
+;
+	HIHEADER	"B/SCR", BSCR, DOCON
+	.data.l	DISK_BUFFER_COUNT
+
+
+
+
+
+

--- a/main.src
+++ b/main.src
@@ -33,7 +33,14 @@
 	.include	"context.inc"
 
 
-	.section	main,    code,  locate=h'8c000000
+; We may have time to move this to flash ROM at h'a0000000 ?
+	.AIFDEF	BUILD_FOR_ROM
+PREBUILT_DICTIONARY_BASE:	.equ	h'a0000000
+	.AELSE
+PREBUILT_DICTIONARY_BASE:	.equ	h'8c000000
+	.AENDI
+
+	.section	main,    code,  locate=PREBUILT_DICTIONARY_BASE
 
 	.org	$
 
@@ -42,16 +49,19 @@
 ;***************************
 ; 0 offset into the ROMmable code
 ORIG:
-	mov.l	#_fCENT, r0
-	jmp 	@r0
+	mov.l	@(_iCENT-$-NATURAL_SIZE,PC), r0	; Cold boot, initializes everything.
+	jmp 	@r0
+	nop
+	nop
+; Wouldn't hurt to uselessly load the warm entry point as we go,
+; but we'll assume that the offsets double for 32 bit addressing CPUs.
 ;***************************
 ;**  W A R M   E N T R Y  **
 ;***************************
 ; 
-; 4 offset into the ROMmable code
-	nop 	; Conveniently left over from the COLD entry point.
-	mov.l	#WENT, r0	; warm-start code, keeps current dictionary intact
+	mov.l	@(_iWENT-$-NATURAL_SIZE,PC), r0	; warm-start code, keeps current dictionary intact
 	jmp 	@r0
+	nop 						; Can't avoid this no-op.
 	nop
 ;
 ;*
@@ -59,7 +69,7 @@ ORIG:
 ;*
 ; All of this is essentially place-holder values:
 COLD_PARAMETERS:
-	.data.l	"SH-3"	; cpu
+	.data.l	"SH-3"	; cpu in revision slot.
 	.data.l 0		; revision 
 	.data.l	0		; topmost word in FORTH vocabulary
 BACKSP:
@@ -70,19 +80,25 @@ SINIT:
 	.data.l	fSP_BASE	; ORIG-$210	; initial top of data stack
 RINIT:
 	.data.l	fRP_BASE	; ORIG-$10	; initial top of return stack
-	.data.l	fSP_LIMIT-h'200	; ORIG-$200	; terminal input buffer
+	.data.l	TERMINAL_INPUT_BUFFER	; ORIG-$200	; terminal input buffer
 	.data.l	31	; initial name field width
 	.data.l	0	; initial warning mode (0 = no disc)
 FENCIN:
-	.data.l	fSP_LIMIT-h'400	; REND	; initial fence
+	.data.l	REND	; initial fence
 DPINIT:
-	.data.l	fSP_LIMIT-h'400	; REND	; cold start value for DP
+	.data.l	REND	; cold start value for DP
 VOCINT:
-	.data.l	fSP_LIMIT-h'400	; FORTH+8	
+	.data.l	FORTH+4*NATURAL_SIZE	
 COLINT:
 	.data.l	132	; initial terminal carriage width
 DELINT:
 	.data.l	4	; initial carriage return delay
+
+COLD_PARAMETER_SIZE:	.equ	$
+_iCENT:
+	.data.l	_fCENT
+_iWENT:
+	.data.l	_fWENT
 ;*
 ;****************************************************
 ;*
@@ -93,6 +109,7 @@ DELINT:
 ; Thus:
 ;
 	.include	"teststuff.inc"
+	
 	.include	"initialize.inc"
 	.include	"primitive.inc"
 	.include	"compiler.inc"
@@ -104,26 +121,115 @@ DELINT:
 	.include	"driver.inc"
 
 
-	.section	user,    data,  locate=h'8c010000
+;
+; ****** Fix this later!
+;
+	HIHEADER	FORTH, ROMFORTH, DODOES, MIMM
+	.data.l	h'81A0, _sTASK
+	.data.l	0
+	.sdata	"Copyright Joel Rees, 2014. Parts Copyright David Lion and Forth Interest Group, 1979"
+
+	HIHEADER	TASK, ROMTASK, DOCOL
+	.data.l	NOOP, SEMIS
+ERAM:
+	.sdata	"Joel Rees"	
+
+
+; The memory map will depart drastically from the fig-FORTH model for many reasons.
+; The biggest is that a buffer and a stack share allocation space is a recipe for disaster.
+; The other biggest reason is that we are no longer nearly so memory-constrained.
+;
+; Also, we want to clearly mark the ROMmable portion and separate it from stuff in RAM.
+;
+
+
+	.AIFDEF	BUILD_FOR_ROM
+RUNTIME_DICTIONARY_BASE:	.equ	h'8c000000
+	.AELSE
+	.align	4
+RUNTIME_DICTIONARY_BASE:	.equ	$
+	.AENDI
+
+
+	.section	dictionary,	data, locate=RUNTIME_DICTIONARY_BASE
+
+; ****** Fix this later!
+;
+;*  These definitions, up through the lable 'REND', are overwritten
+;*  at time of cold load and should have the same contents
+;*  as shown here:
+;*
+	HIHEADER	FORTH, FORTH, DODOES, MIMM
+	.data.l	h'81A0, _sTASK
+	.data.l	0
+;
+	.sdata	"Copyright Joel Rees, 2014. Parts Copyright David Lion and Forth Interest Group, 1979"
+
+
+	HIHEADER	TASK, TASK, DOCOL
+	.data.l	NOOP, SEMIS
+;
+REND:	.equ	$	; ( first empty location in dictionary )
+;
+	.res.b	RUNTIME_DICTIONARY_SIZE-(REND-RUNTIME_DICTIONARY_BASE)
+RUNTIME_DICTIONARY_END:	.equ	$
+	.res.b	ALLOC_GAP
+	.align	4
+RUNTIME_DICTIONARY_SPACE_END:	.equ	$
+
+
+	.section	user,    data,  locate=RUNTIME_DICTIONARY_SPACE_END
+	.res.b	ALLOC_GAP
 PER_USER:	.equ $
-	.res.b	UTABLESZ
-	
-	.section	pstack,  stack, locate=PER_USER+h'E000
+	.res.b	UTABLESZ*N_USERS
+PER_USER_END:	.equ	$
+	.res.b	ALLOC_GAP
+	.align	4
+PER_USER_SPACE_END:	.equ	$
+
+
+; Should be in per-user space, but it's not that way in the fig model:
+	.section	iobuffers,    data,  locate=PER_USER_SPACE_END
+IO_SPACE_BASE:	.equ	$
+	.res.b	ALLOC_GAP
+TERMINAL_INPUT_BUFFER:	.equ $
+	.res.b	TERMINAL_INPUT_BUFFER_SIZE
+TERMINAL_INPUT_BUFFER_END:	.equ	$
+	.res.b	ALLOC_GAP
+	.align	4
+	.res.b	ALLOC_GAP
+DISK_BUFFERS:
+	.res.b	DISK_BUFFER_RECORD_SIZE*DISK_BUFFER_COUNT
+DISK_BUFFERS_END:	.equ	$
+	.res.b	ALLOC_GAP
+	.align	4
+	.res.b	ALLOC_GAP
+RAM_DISK_BASE:
+	.res.b	RAM_DISK_SIZE
+RAM_DISK_END	.equ	$
+	.res.b	ALLOC_GAP
+	.align	4
+IO_SPACE_END:	.equ	$
+
+
+	.section	pstack,  stack, locate=IO_SPACE_END
+	.res.b	ALLOC_GAP
 fSP_LIMIT:	.equ $
-	.res.b		h'1F00
+	.res.b		PARAMETER_STACK_SIZE
 fSP_BASE:	.equ $
+	.res.b	ALLOC_GAP
+	.align	4
+fSP_END:	.equ	$
 
-	.section	rstack,  stack, locate=h'8c01FF00
+	.section	rstack,  stack, locate=fSP_END
+	.res.b	ALLOC_GAP
 fRP_LIMIT:	.equ $
-	.res.b		h'100
-fRP_BASE:	.equ $
-	
-	.section	thevoid, dummy, locate=h'8c020000
-OUTERSPACE:	.equ $
-
-	
-
+	.res.b		CONTROL_STACK_SIZE
+fRP_BASE:	.equ h'8c020000-ALLOC_GAP
+	.res.b	ALLOC_GAP
+	.align	4
+fRP_END:	.equ	$
 
 
 
-	.end
\ No newline at end of file
+	.end

--- a/teststuff.inc
+++ b/teststuff.inc
@@ -56,6 +56,8 @@ COMPIL:	.define	"NOOP"	; used in SEMI
 SMUDGE:	.define	"NOOP"	; used in SEMI
 LBRAK:	.define	"NOOP"	; used in SEMI
 COMMA:	.define	"NOOP"	; used in CONSTANT
+DODOES:	.define	"NOOP"	; used in ROMFORTH
+DOVOC:	.define	"NOOP"	; used in ROMFORTH
 ; :	.define	"NOOP"