diff options
Diffstat (limited to 'programs')
| -rw-r--r-- | programs/subasm.s | 239 |
1 files changed, 239 insertions, 0 deletions
diff --git a/programs/subasm.s b/programs/subasm.s new file mode 100644 index 0000000..fe02794 --- /dev/null +++ b/programs/subasm.s @@ -0,0 +1,239 @@ +; SuBAsm +; The Sux Bootstrapped Assembler. +; +; by mr b0nk 500 <b0nk@b0nk.xyz> + +; Variables +.org $1000 +prg_name: + .byte "SuBAsm" +ver_txt: + .byte ", version " +ver_num: + .byte "0.1" +x: + .word $0 +y: + .word $0 + +str_buf: + +; Input buffer. +.org $2000 +buf: + +; Control Register. +.org $C000 +ctrl_reg: + +; Screen. +.org $C001 +scr: + +; Keyboard. +.org $C002 +kbd: + +; Main program. +.org $0 +reset: + cps + ldx.w #$FFFF + txs + ldy #$0 + jsr clr_buf + ldx.w #$0 ; Reset x. + ldy #$0 ; Reset y. + jmp print_title + +read: + lda ctrl_reg ; Is the keyboard ready? + beq read ; Loop until the keyboard is ready. + lda #$0 ; Start resetting the control register. + sta ctrl_reg ; Reset the control register. + jmp getchar ; We got a key. + +rset_x: + + ldx #$0 ; Reset x. + stx.w x + rts + +print_title: + lda prg_name, x + beq print_ver ; Did we find a null terminator? + sta ; Print character. + inx ; Increment offset. + inc x + jmp print_title ; Keep printing more characters. + +print_ver + jsr rset_x + lda ver_txt, x + beq print_num ; Did we find a null terminator? + sta scr ; Print character. + inx ; Increment offset. + jmp print_ver ; Keep printing more characters. + +print_num: + lda ver_num, x + beq getline ; Did we find a null terminator? + sta scr ; Print character. + inx ; Increment offset. + jmp print_num ; Keep printing more characters. +getline: + lda #$A + sta scr ; Print newline + inc y + jsr rset_x + jmp read + +getchar: + lda kbd ; Get typed character. + cmp #$1B ; Did the user type an escape? + beq esc ; Yes, so start getting the escape code. + cmp #$A ; Did the user type a newline? + beq nl ; Yes, so start parsing the input. + cmp #$8 ; Did the user type a backspace? + beq bs ; Yes, so start checking the buffer. + jsr echo ; Print character to screen. + +store_char: + sta buf, y ; Store typed character into the input buffer. + iny ; Increment buffer offset. + jmp read ; Get another character. + +esc: + lda ctrl_reg ; Skip the '['. + lda ctrl_reg ; Get the next character. + beq read ; We have an error, so discard it, and read the next character. + lda kbd ; Get the escape code. + cmp #$41 ; Did the user press the up arrow? + beq up ; Yes, so move the cursor up. + cmp #$42 ; Did the user press the down arrow? + beq down ; Yes, so move the cursor down. + cmp #$43 ; Did the user press the left arrow? + beq left ; Yes, so move the cursor left. + cmp #$44 ; Did the user press the right arrow? + beq right ; Yes, so move the cursor right. + +up: + lda #$1B + sta scr + lda #$5B + sta scr + lda #$41 + sta scr + jmp read +down: + lda #$1B + sta scr + lda #$5B + sta scr + lda #$42 + sta scr + jmp read +left: + lda #$1B + sta scr + lda #$5B + sta scr + lda #$43 + sta scr + jmp read +right: + lda #$1B + sta scr + lda #$5B + sta scr + lda #$44 + sta scr + jmp read + + + +nl: + sta scr ; Print newline. + lda #$0 ; Put a null terminator, in place of the newline. + sta buf, y ; Place it into the input buffer. + ldy.w #$0 ; Reset y, to parse the input. + jmp parse + +back: + jsr echo ; Print backspace. + lda #$0 ; Put a null terminator, in place of the backspace. + sta buf, y ; Place it into the input buffer. + dey ; Decrement buffer offset. + jmp read ; Get next character. + +bs: + cpy #$0 ; Are we at the start of the buffer? + beq read ; We are, so do not store the backspace into the buffer. + jmp back ; We are not, so add the backspace to the buffer. + +parse: + lda buf, y + beq clr_buf ; Reset y, if we hit the null terminator. + sta scr ; Print 'You have typed, ' + iny ; Increment offset. + jmp result ; Keep printing. + +rset_y: + ldy.w #$0 + jmp print_buf ; Print the input buffer. + +print_buf: + lda buf, y ; Get a character from the input buffer. + beq fin ; Are we done with printing the buffer? + sta scr ; Print said character. + iny + jmp print_buf ; Keep printing the buffer. + +spin: + nop + nop + nop + jmp spin + +clr_buf: + lda #$0 + cpy.w #$1000 + beq clr_end + sta buf, y + iny + jmp clr_buf +clr_sbuf: + lda #$0 + cpy.w #$40 + beq clr_end + sta str_buf, y + iny + jmp clr_sbuf + +clr_end: + rts + +echo: + sta scr ; Echo typed character. + rts ; Return. + +.org $FFC0 +.qword reset + +.org $FF50 +.qword spin +.qword spin +.qword spin +.qword spin +.qword spin +.qword spin +.qword spin + +.org $FFA0 +.qword irq_routine +;.org $0 +;viewmem +;.org $100 +;viewmem +;q +done |