diff options
| -rw-r--r-- | constants.asm | 3 | ||||
| -rw-r--r-- | isr.asm | 19 | ||||
| -rw-r--r-- | kernel.asm | 39 |
3 files changed, 49 insertions, 12 deletions
diff --git a/constants.asm b/constants.asm index ac6438a..16f7510 100644 --- a/constants.asm +++ b/constants.asm @@ -7,6 +7,9 @@ MAX_COLS equ 80 LENGTH_ROW equ 0A0h ; NOTE: length in bytes (80 * 2 = 160) LENGTH_COL equ 02h ; NOTE: length in bytes (1 * 2 = 2) +ISR_TEST equ 20h +ISR_MINOS equ 21h + %include "colors.asm" %include "ascii.asm" ; ASCII control codes %include "scancodes.asm" ; Keyboard scancodes @@ -1,5 +1,22 @@ int21: - nop + cmp al, .fn_table_size + jg .return + + push bx + push di + movsx bx, al + mov di, .fn_table + call [di+bx] + pop di + pop bx + + .return: + iret + + .fn_table: + dw memset + dw memcpy + .fn_table_size dw $-.fn_table int22: nop int20: @@ -88,6 +88,14 @@ kmain: jle .info_disk_loop ; continue .preload: + push ISR_TEST + push int20 + call isr_inject + + int 20h ; test routine + + push ISR_MINOS + push int21 call isr_inject .mainloop: @@ -105,31 +113,40 @@ isr_inject: push es push ax push bx - push bp + push cx + push di + push ds - mov ax, 0000h ; set ES to Interrupt Vector Table + mov ax, 0000h ; set DS/ES to Interrupt Vector Table ; (start of RAM) mov es, ax + mov ds, ax - mov bp, 20h * 4 ; Set vector (v = es:offset * 4)) - lea bx, [int22] ; Load address of ISR routine - mov ax, cs ; Load code segment into AX + ;mov bp, 20h * 4 ; Set vector (v = es:offset * 4)) + ;lea bx, [int22] ; Load address of ISR routine + mov bx, [bp + 4] ; ISR routine + mov di, [bp + 6] ; IVT offset + shl di, 2 ; IVT * 4 - mov word [es:bp], bx ; Store address of ISR routine - mov word [es:bp+2], ax ; Store code segment of ISR routine + mov ax, cs ; Load code segment into AX + mov word [ds:di], bx ; Store address of ISR routine + mov word [ds:di+2], ax ; Store code segment of ISR routine + pop ds ; Restore DS so we can print push bx push ax + push word [bp + 6] push msg_isr_fmt call printf ; print injected ISR address - add sp, 2 * 3 ; cleanup stack + add sp, 2 * 4 ; cleanup stack - pop bp + pop di + pop cx pop bx pop ax pop es - int 20h ; test new ISR + ;int 20h ; test new ISR mov sp, bp pop bp @@ -164,7 +181,7 @@ msg_entry_point_fmt: db 'Kernel address: %5x:%4x - %5x:%4x (%d:%d - %d:%d)\n' db 'Stack address : %5x:%4x (%d:%d)\n' db 'Boot device : %2x\n\n', 0 -msg_isr_fmt: db "ISR %5x:%4x\n", 0 +msg_isr_fmt: db "ISR %2xh, %5x:%4x\n", 0 ; Error messages error_msg_panic: db "PANIC: ", 0 |