From b6ac63225524f1b34ffc4f780726ed981ba7e6a2 Mon Sep 17 00:00:00 2001
From: Jan Tuomi <jan@jantuomi.fi>
Date: Fri, 12 Apr 2024 22:28:40 +0300
Subject: Add "@include %bootstrap" directive format for including builtin
 bootstrap file

---
 atk16_asm/asm_pass0.py                |  9 +++-
 atk16_asm/builtin_asm/bootstrap.atk16 | 78 +++++++++++++++++++++++++++++++++++
 2 files changed, 86 insertions(+), 1 deletion(-)
 create mode 100644 atk16_asm/builtin_asm/bootstrap.atk16

(limited to 'atk16_asm')

diff --git a/atk16_asm/asm_pass0.py b/atk16_asm/asm_pass0.py
index f6586cd..b30ddc0 100644
--- a/atk16_asm/asm_pass0.py
+++ b/atk16_asm/asm_pass0.py
@@ -29,7 +29,14 @@ def pass_0(lines: list[str], file_name: str) -> Result0:
     match keyword:
       case "@include":
         asm_file_name = args[0] if args[0].endswith(".atk16") else args[0] + ".atk16"
-        path = os.path.join(os.path.dirname(file_name), asm_file_name)
+        # if starts with %, use the path relative to this source file, not the current working directory
+        if asm_file_name.startswith("%"):
+          path = os.path.join(os.path.dirname(__file__), "builtin_asm", asm_file_name[1:])
+        # if absolute, use the absolute path
+        elif os.path.isabs(asm_file_name):
+          path = asm_file_name
+        else:
+          path = os.path.join(os.path.dirname(file_name), asm_file_name)
         with open(path, "r") as f:
           incl_lines = f.readlines()
 
diff --git a/atk16_asm/builtin_asm/bootstrap.atk16 b/atk16_asm/builtin_asm/bootstrap.atk16
new file mode 100644
index 0000000..9b024e6
--- /dev/null
+++ b/atk16_asm/builtin_asm/bootstrap.atk16
@@ -0,0 +1,78 @@
+@let SP              RH
+
+; vector table fields
+@let vector_table    0x10
+@let vt_ISR0         0x10 ; ISR0
+@let vt_ISR1         0x11 ; ISR1
+@let vt_ISR2         0x12 ; ISR2
+@let vt_ISR3         0x13 ; ISR3
+@let vt_stack_addr   0x14 ; Stack address
+@let vt_term_pp_addr 0x15 ; Terminal peripheral address
+@let vt_kb_pp_addr   0x16 ; Keyboard peripheral address
+@let vt_gr_mode_addr 0x17 ; Graphics mode setting address
+@let vt_sprite_mem   0x18 ; Sprite memory address
+@let vt_text_mem     0x19 ; Text memory buffer address
+
+; memory segments
+@let stack_segment   0x8000
+@let mmio_segment    0xE000
+@let terminal_addr   0xE000
+@let keyboard_addr   0xE001
+@let gr_mode_addr    0xE002
+@let sprite_mem      0xE800
+@let text_mem        0xF800 ; to 0xFFFF
+; note: sprite memory & text memory can use the same space
+; since they are never used at the same time
+
+; graphics mode settings
+@let gr_disabled_mode 0b00
+@let gr_text_mode     0b01
+@let gr_sprite_mode   0b10
+
+@address vector_table
+  keyboard_isr   ; 0x10
+  hlt_isr        ; 0x11
+  hlt_isr        ; 0x12
+  hlt_isr        ; 0x13
+  stack_segment  ; 0x14
+  terminal_addr  ; 0x15
+  keyboard_addr  ; 0x16
+  gr_mode_addr   ; 0x17
+  sprite_mem     ; 0x18
+  text_mem       ; 0x19
+
+@label hlt_isr
+  ldi 0x55 RE
+  hlt
+
+@label keyboard_isr
+  spu RA
+  spu RB
+  ldi vt_kb_pp_addr RA    ; RA := Keyboard peripheral address pointer
+  ldr RA RA               ; RA := Keyboard peripheral address deref
+  ldr RA RA               ; RA := <16-bit keyboard character code> from MMIO register
+  ldi vt_term_pp_addr RB  ; RB := Terminal peripheral address pointer
+  ldr RB RB               ; RB := Terminal peripheral address deref
+  str RA RB               ; terminal <- character code (ASCII?)
+  mov RA RE               ; RE := character code (for debugging)
+  spo RB
+  spo RA
+  rti
+@label program_segment
+
+; define short prelude that sets up vital instructions
+; NOTE: must be shorter than the vector table offset
+@address 0x0
+; set up stack pointer to point to beginning of stack segment
+  ldi vt_stack_addr RA
+  ldr RA SP
+  jpi program_segment
+
+@address program_segment
+; set graphics mode to disabled
+  ldi vt_gr_mode_addr RA
+  ldr RA RA
+  ldi gr_disabled_mode RB
+  str RB RA
+; jump to main (user defined)
+  jpi main
-- 
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