commit 9bf77f0cd30845c8d018242ee6ca2dbe3627ba09
parent d03eb65da9ad16272c07b03e1577f535f26c5109
Author: Christian Ermann <christianermann@gmail.com>
Date: Sat, 26 Oct 2024 11:55:01 -0700
Add 'interpret', 'branch', and 'quit'
Diffstat:
| M | forth.s | | | 46 | ++++++++++++++++++++++++++++++++++++---------- |
1 file changed, 36 insertions(+), 10 deletions(-)
diff --git a/forth.s b/forth.s
@@ -9,7 +9,9 @@
#define psp sp
#define rsp s2
-#define cell 4
+#define cell 4
+#define dcell 8
+
#define flag_offset 4
#define name_len_offset 5
#define name_offset 6
@@ -45,7 +47,7 @@
.endm
.macro push_ret reg
- store_cell \reg -cell(rsp)
+ store_cell \reg, -cell(rsp)
addi rsp, rsp, -cell
.endm
@@ -72,13 +74,12 @@ name_\label:
code_\label: # 8. This is where our assembly code will go.
.endm
-.macro defword name, name_length, flags, label
+.macro defword name, name_length, flags, label, last
.section ".rodata"
.balign cell
.globl name_\label
name_\label:
- .int link
- .equ link, name_\label
+ .int name_\last
.byte \flags
.byte \name_length
.ascii "\name"
@@ -88,6 +89,11 @@ name_\label:
.int docol
.endm
+docol:
+ push_ret ip
+ addi ip, w, cell
+ NEXT
+
.equ name_null, 0
defcode "exit", 4, 0, exit, null
@@ -191,7 +197,7 @@ to_cfa_impl:
add t0, t0, t1
add w, w, t0
addi w, w, 3
- andi w, w, 0xFFFFFFF4
+ andi w, w, 0xFFFFFFFC
ret
defcode "execute", 7, 0, execute, to_cfa
@@ -200,24 +206,44 @@ defcode "execute", 7, 0, execute, to_cfa
jr x
# 'next' should be called by the executed word
+defcode "interpret", 9, 0, interpret, execute
+ jal word_impl
+ jal find_impl
+ beqz w, _not_found
+ jal to_cfa_impl
+ load_cell x, 0(w)
+ jr x
+_not_found:
+ next
+
+defcode "branch", 6, 0, branch, interpret
+ load_cell t0, 0(ip)
+ add ip, ip, t0
+ next
+
+defword "quit", 4, 0, quit, branch
+ .int interpret
+ .int branch
+ .int -dcell
+
.section ".rodata"
program:
.int type
- .int word
- .int find
- .int to_cfa
- .int execute
+ .int quit
version_string:
.ascii "soup forth rv32\n"
version_string_len = (. - version_string)
word_buffer: .space 255
+return_stack: .space 512
+return_stack_top:
latest: .int name_find
.section ".text.boot"
start:
la psp, __stacktop
+ la rsp, return_stack_top
la ip, program
push_addr version_string
