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Working hex parsing in monitor

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Daniele Verducci su MatissePenguin 2020-11-25 20:50:39 +01:00
parent 336f2fe181
commit 229ba1d48d
1 changed files with 54 additions and 2 deletions
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56
assembly/bios/monitor.asm
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@ -5,7 +5,7 @@
; H (HELP) Shows available commands ; H (HELP) Shows available commands
; D (DUMP) $pos Dumps first 100 bytes of memory starting at $pos ; D (DUMP) $pos Dumps first 100 bytes of memory starting at $pos
; S (SET) $pos $val Replaces byte at $pos with $val ; S (SET) $pos $val Replaces byte at $pos with $val
; L (LOAD) $pos $val Loads all the incoming bytes in memory starting from $pos ; L (LOAD) $pos $val Loads all the incoming bytes in memory starting from $pos. Ends when "0" is received 8 times.
; R (RUN) $pos Starts executing code from $pos ; R (RUN) $pos Starts executing code from $pos
; The commands are entered with a single letter and the program completes the command ; The commands are entered with a single letter and the program completes the command
@ -19,7 +19,7 @@ MON_COMMAND_DUMP: DB "DUMP",0
MON_COMMAND_SET: DB "SET",0 MON_COMMAND_SET: DB "SET",0
MON_COMMAND_LOAD: DB "LOAD",0 MON_COMMAND_LOAD: DB "LOAD",0
MON_COMMAND_RUN: DB "RUN",0 MON_COMMAND_RUN: DB "RUN",0
MON_ARG_HEX: DB "0x",0 MON_ARG_HEX: DB " 0x",0
MON_HELP: DB 10,"Available commands: HELP, DUMP, SET, LOAD, RUN",0 MON_HELP: DB 10,"Available commands: HELP, DUMP, SET, LOAD, RUN",0
MON_ERR_SYNTAX: DB " Syntax error",0 MON_ERR_SYNTAX: DB " Syntax error",0
@ -70,6 +70,7 @@ monitor_help:
monitor_dump: monitor_dump:
ld bc, MON_COMMAND_DUMP + 1 ; autocomplete command ld bc, MON_COMMAND_DUMP + 1 ; autocomplete command
call Print call Print
call monitor_arg_byte
jp monitor_main_loop jp monitor_main_loop
monitor_set: monitor_set:
@ -88,5 +89,56 @@ monitor_run:
jp APP_VAR_SPACE ; Start executing code jp APP_VAR_SPACE ; Start executing code
jp monitor_main_loop jp monitor_main_loop
monitor_arg_byte:
; Print 0x... prompt
ld bc, MON_ARG_HEX
call Print
; Receive two hex digits
call monitor_readHexDigit
call monitor_readHexDigit
ret
monitor_arg_2byte:
; Print 0x... prompt
ld bc, MON_ARG_HEX
call Print
; Receive four hex digits
call monitor_readHexDigit
call monitor_readHexDigit
call monitor_readHexDigit
call monitor_readHexDigit
ret
monitor_readHexDigit:
call Readc
; check if is a valid hex digit (0-9 -> ascii codes 48 to 57; A-F -> ascii codes 65 to 70)
; first check if is between 0 and F(ascii codes 48 to 70)
ld b, a
sub a, 48
jp m, monitor_readHexDigit ; if negative (s), ascii code is under 48: ignore char
ld a, b
sub a, 71 ; 71 because we want to include 70 and the result must be negative
jp p, monitor_readHexDigit ; if not negative (ns), ascii code is over 70: ignore it
; check if is a valid int (<=57)
ld a, b
sub a, 58
jp p, monitor_readHexDigit_char ; if not negative (ns), maybe is a char
; otherwise is a number! First print for visive feedback
ld a, b
call Printc
; then convert to its value subtracting 48
sub a, 48
ret
monitor_readHexDigit_char:
; check if is A, B, C, D, E, F (ascii codes 65 to 70). We already checked it is less than 70.
ld a, b
sub a, 65
jp m, monitor_readHexDigit ; if negative (s), ascii code is under 65: ignore char
; otherwise is a valid char (A-F). Print for visive feedback
ld a, b
call Printc
; Its numeric value is 10 (A) to 15 (F). To obtain this, subtract 55.
sub a, 55
ret