Fix bug in assembler where long jumps with jpi got aliased

3 files changed, 37 insertions, 30 deletions

diff --git a/atk16_asm/asm_ops.py b/atk16_asm/asm_ops.py
index a7ef88f..3198d4c 100644
--- a/atk16_asm/asm_ops.py
+++ b/atk16_asm/asm_ops.py
@@ -126,6 +126,10 @@ def make_jpi(meta: Meta, symbols: Symbols, imm: int | str) -> int:
   """JPI 0110 XXXI IIII IIII"""
   imm_e = eval_expr(symbols, str(imm), bits=9)
   imm_e = imm_e - meta.address - 1
+
+  if imm_e < -(2 ** 8) or imm_e >= 2 ** 8:
+    raise Exception(f"jpi imm value is not representable in 9 bits: {imm_e}")
+
   imm_e = imm_e & (0b111111111)
   word = (0b0110 << 12) + \
               imm_e
diff --git a/atk16_emu/emu.py b/atk16_emu/emu.py
index d519e5f..67f63f1 100644
--- a/atk16_emu/emu.py
+++ b/atk16_emu/emu.py
@@ -355,9 +355,13 @@ class Machine:
           self.pc.value = addr
 
         case JPI(imm):
+          # check that imm fits in 9 bits
+          if imm >= 2 ** 9:
+            raise Exception(f"JPI immediate value does not fit in 9 bits: {imm:>04x}" )
+
           # convert imm from signed (twos complement) 9-bit to a python int
-          imm = (imm & (0b011111111)) - (imm & 0b100000000)
-          self.pc.value = (self.pc.value + imm) & 0xFFFF
+          py_imm = (imm & (0b011111111)) - (imm & 0b100000000)
+          self.pc.value = (self.pc.value + py_imm) & 0xFFFF
 
         case BRR(flag, addr_reg):
           if self.check_nth_flag(flag):
@@ -407,6 +411,7 @@ class Machine:
   def decode(self, instr: int):
     opcode = (instr & 0xF000) >> 12
     opdata = instr & 0x0FFF
+
     match opcode:
       case 0b0000: return ALR(target=(opdata & 0b111000000000) >> 9,
                               left=(opdata & 0b000111000000) >> 6,
diff --git a/atk16_projects/monitor/monitor.atk16 b/atk16_projects/monitor/monitor.atk16
index 57db870..4580d5f 100644
--- a/atk16_projects/monitor/monitor.atk16
+++ b/atk16_projects/monitor/monitor.atk16
@@ -83,9 +83,10 @@
   ; BEGIN critical section
   m_set_critical RA RB
 
-  calli is_newline_pressed
-  subi RG 1 RG                ; if is_newline_pressed() == 1, then loop_newline_pressed
-  bri zero loop_newline_pressed
+  ; TODO evaluate input_buffer if newline was just pressed
+  ;calli is_newline_pressed
+  ;subi RG 1 RG                ; if is_newline_pressed() == 1, then loop_newline_pressed
+  ;bri zero loop_newline_pressed
   jpi loop_finally
 
 @label loop_newline_pressed
@@ -141,27 +142,6 @@
   stack_restore RA RB RC RD RE
   return
 
-
-@label is_newline_pressed
-  ; check if the last character in the input buffer is a newline
-  ; parameters:               none
-  ; returns:                  RG = 1 if newline is pressed, 0 otherwise
-  stack_stash RA RB
-  ldi 10 RB                   ; RB := newline character
-
-  ldi input_cursor_p RA       ; RA := data segment pointer
-  ldr RA RA                   ; RA := 0xE802
-  ldr RA RA                   ; RA := &char
-  ldr RA RA                   ; RA := char
-
-  ldi 1 RG                    ; RG := 1
-  sub RA RB RA                ; if RA == newline, then return RG = 1
-  bri zero is_newline_pressed_done
-  ldi 0 RG                    ; else return RG = 0
-@label is_newline_pressed_done
-  stack_restore RA RB
-  return
-
 @data row_index_mask ${64 - 1}
 
 @label keyboard_isr
@@ -170,15 +150,15 @@
   ldr RA RA               ; RA := Keyboard peripheral address deref
   ldr RA RA               ; RA := <16-bit keyboard character code> from MMIO register
 
+  ldi text_cursor_p RC
+  ldr RC RC
+  ldr RC RC               ; RC := text_cursor_p
+
   mov RA RB               ; RB := character code
   subi RB 5 RB            ; if code == 10 (enter key), then run newline handler
   subi RB 5 RB
   bri zero keyboard_isr_newline
 
-  ldi text_cursor_p RC
-  ldr RC RC
-  ldr RC RC               ; RC := text_cursor_p
-
   mov RA RB               ; if code == 8 (backspace key), then run backspace handler
   subi RB 5 RB
   subi RB 3 RB
@@ -203,6 +183,24 @@
 @label keyboard_isr_newline
   m_newline RA RB
 
+  ; note: RC = text_cursor_p, set in the beginning of the ISR
+
+  ; BEGIN memcopy(last_line_p, input_buffer_p, input_buffer_size)
+  slri RC 6 RC             ; RC := RC >> 6, i.e. the row index
+  slli RC 6 RC             ; RC := RC << 6, i.e. index to the first character of the row
+  addi RC 3 RA            ; RA := RC + 3, i.e. index to the first character of the input string
+
+  ldi input_buffer_p RB
+  ldr RB RB               ; RB := &input_buffer_p
+  ldr RB RB               ; RB := input_buffer_p
+
+  ldi input_buffer_size RC
+  ldr RC RC               ; RC := input_buffer_size
+
+  ldi memcopy RD
+  callr RD
+  ; END
+
   ldi prompt_string RA
   calli put_string