Hi amForth-ers,
Any platform that can be targeted by a cross-platform tool chain supporting
C (or other high level language) can host amForth. An example is given
below:
1) Define a container array for amForth's volatile storage (eg variables,
stack ...)
unsigned long xu4amForth[1024]; // size storage accordingly
2)Depends on your target platform - below is an example for CH32 - check
assembly listing
to verify where the storage was allocated
#
-----------------------------------------------------------------------------
# Memory map for Flash and RAM
#
-----------------------------------------------------------------------------
.equ RamStart, 0x20000100 # Start of RAM Porting: Change this !
.equ RamEnd, 0x20001100 # End of RAM. 20 kb. Porting: Change this !
.equ FlashStart, 0x00000000 # Start of Flash Porting: Change this !
.equ FlashEnd, 0x0000F230 # End of Flash. 62 kb. Porting: Change this !
3) So far I haven't seen any register conflicts between amForth and C
routines/host assembler routines.
4) amForth's dictionary core words, shared and platform words reside in
flash, the user defined words/variables are
being stored in the ram container in 1) above.
5)Core (foundation) words depends on your target platform for build: use
risc-v/words for RISCV (amForth), arm/words for ARM32 (amForth) and
i386/words for
i386 (these can be borrowed from seedForth-GitHub - may have some
incompatibility here - based on deviation from
the 2012 forth standard words). On a PC there is no flash memory so the
assembler built dictionary words (core/shared)
sits in the executable image and the PC C compiler can be used to build the
executable.
6) Platform words would need to be modified appl/.../words (amForth) -
there are not too many of them
7) It is easier and less time consuming to let the C do the heavy lifting
(startup, initialization of peripherals, drivers,
interrupt handling, networking, file handling ...)
8) As an example C applications can work with amForth using:
register long * x2_Reg asm ("sp"); // x2/SP RSP Return Stack Pointer
(sp is same as x2)
register long * x3_Reg asm ("gp"); // TOS Top Of Stack (gp is same as
x3)
register long * x4_Reg asm ("tp"); // tp DSP Data Stack Pointer (tp is
same as x4)
register long * x8_Reg asm ("s0"); // x8 loop index (s0 is same as x8)
register long * x9_Reg asm ("s1"); // x9 loop limit (s1 is same as x9)
register long * x16_Reg asm ("a6"); // x16 IP Forth VM IP register
(ITC Instruction Pointer) (a6 is same as x16))
register long * x17_Reg asm ("a7"); // x17 W Forth VM W register (a7
is same as x17)
x17_Reg = XT_addressArray[xt_code]; // copy xt address into amForth VM
W register
asm("Call DO_EXECUTE");
Appears to work but is still experimental.
Regards,
John S
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