Add help command eval

2 files changed, 112 insertions, 14 deletions

diff --git a/atk16_asm/builtin_asm/std_mem.atk16 b/atk16_asm/builtin_asm/std_mem.atk16
index 43d00ea..5855879 100644
--- a/atk16_asm/builtin_asm/std_mem.atk16
+++ b/atk16_asm/builtin_asm/std_mem.atk16
@@ -41,3 +41,65 @@
 @label memcopy_done
   stack_restore RD RE RF
   return
+
+@label memcompare
+  ; compares two blocks of memory
+  ; parameters:             RA = src1 (source address 1)
+  ;                         RB = src2 (source address 2)
+  ;                         RC = n (number of words to compare)
+  ; returns:                RG = 1 if the blocks are equal, 0 otherwise
+  stack_stash RA RB RC RD RE
+  ldi 0 RG                  ; RD := 0 (result)
+
+@label memcompare_loop
+  subi RC 0 RC
+  bri zero memcompare_result_equal   ; exit the loop
+
+  ldr RA RD                 ; RD := left value
+  ldr RB RE                 ; RE := right value
+
+  sub RD RE RD              ; RD := left - right
+  bri zero memcompare_continue      ; if left == right, continue the loop
+
+  jpi memcompare_end        ; if left != right, exit the loop
+
+@label memcompare_continue
+  inc RA                    ; RA := RA + 1
+  inc RB                    ; RB := RB + 1
+  dec RC                    ; RC := RC - 1
+  jpi memcompare_loop       ; repeat the loop
+
+@label memcompare_result_equal
+  ldi 1 RG                  ; RG := 1 (result)
+
+@label memcompare_end
+  stack_restore RA RB RC RD RE
+  return
+
+
+@label string_compare
+  ; compares two strings
+  ; parameters:             RA = str1 (source address 1)
+  ;                         RB = str2 (source address 2)
+  ; returns:                RG = 1 if the strings are equal, 0 otherwise
+
+  stack_stash RA RB RC RD RE
+  ldi 0 RG                  ; RD := 0 (result)
+
+  ldr RA RD                 ; RD := left string length
+  ldr RB RE                 ; RE := right string length
+
+  sub RD RE RD              ; RD := left length - right length
+  bri zero string_compare_same_length      ; if equal length, use memcompare
+
+  jpi string_compare_end    ; else if different length, exit
+
+@label string_compare_same_length
+  inc RA
+  inc RB
+  mov RE RC
+  calli memcompare          ; return value implicitly returned in RG
+
+@label string_compare_end
+  stack_restore RA RB RC RD RE
+  return
diff --git a/atk16_projects/monitor/monitor.atk16 b/atk16_projects/monitor/monitor.atk16
index 4ec1205..65e83d1 100644
--- a/atk16_projects/monitor/monitor.atk16
+++ b/atk16_projects/monitor/monitor.atk16
@@ -13,12 +13,12 @@
 ; 0xE800 - 0xEFFF: sprite buffer space that is unused in this program
 @data text_cursor_p       0xE800
 @data input_string_p      0xE801
-@data input_cursor_p      0xE802
-@data input_entered_bool  0xE803
+@data input_entered_bool  0xE802
 
 @data title_string    " »» ATK16 monitor v0.1 »»"
 @data subtitle_string " Run [help] for a list of commands"
 @data prompt_string   " > "
+@data help_cmd_string "help"
 
 @label main
   ; initialize heap allocator
@@ -41,12 +41,6 @@
   str RG RA
   ; END
 
-  ; BEGIN input_cursor_p = input_string_p
-  ldi input_cursor_p RA
-  ldr RA RA
-  str RG RA
-  ; END
-
   ; BEGIN input_entered_bool = 0
   ldi input_entered_bool RA
   ldr RA RA
@@ -80,8 +74,15 @@
   calli put_string
   ; END
 
-  m_newline RA RB
-  m_newline RA RB
+  ; BEGIN print two newlines
+  ldi text_cursor_p RA
+  ldr RA RA
+  ldr RA RB
+  slri RB 6 RB
+  addi RB 2 RB
+  slli RB 6 RB
+  str RB RA
+  ; END
 
   ldi prompt_string RA
   calli put_string
@@ -101,7 +102,17 @@
   ldi 0 RB                      ; else, run this branch and set input_entered_bool = 0
   str RB RA
 
-@data eval_output_string "command received: "
+  ldi help_cmd_string RA
+  ldi input_string_p RB
+  ldr RB RB
+  ldr RB RB
+
+  calli string_compare
+  subi RG 1 RG
+  bri zero loop_input_cmd_help
+
+@label loop_input_not_recognized
+@data eval_output_string "Unknown command: "
   ldi eval_output_string RA
   calli put_string
 
@@ -109,12 +120,26 @@
   ldr RA RA
   ldr RA RA
 
-  calli put_string
+@data put_string_p put_string
+  ldi put_string_p RB
+  ldr RB RB
+  callr RB
+  jpi loop_input_print_newline
+
+@label loop_input_cmd_help
+@data help_cmd_output_0 "Available commands:\n  help    display this help message"
+  ldi help_cmd_output_0 RA
+  ldi put_string_p RB
+  ldr RB RB
+  callr RB
 
+@label loop_input_print_newline
   m_newline RA RB
 
   ldi prompt_string RA
-  calli put_string
+  ldi put_string_p RB
+  ldr RB RB
+  callr RB
 
 @label loop_finally
   m_clear_critical RA RB
@@ -142,7 +167,9 @@
   subi RB 5 RB
   subi RB 3 RB
 
-  ldi keyboard_isr_backspace RD
+@data keyboard_isr_backspace_p keyboard_isr_backspace
+  ldi keyboard_isr_backspace_p RD
+  ldr RD RD
   brr zero RD
 
   ldi row_index_mask RD   ; else code is not special; write it to text buffer
@@ -257,8 +284,17 @@
   bri zero put_string_done    ; i.e. no more characters to put
 
   ldr RC RA                   ; RA := character to put
+  subi RA 5 RD
+  subi RD 5 RD
+  bri zero put_string_newline
+
   m_put_char RA RD RE         ; inline the put_char subroutine to avoid function call overhead
+  jpi put_string_continue
+
+@label put_string_newline
+  m_newline RD RE
 
+@label put_string_continue
   inc RC
   subi RB 1 RB
   jpi put_string_loop