diff options
Diffstat (limited to 'bootblocks/com_bcc.s')
| -rw-r--r-- | bootblocks/com_bcc.s | 65 |
1 files changed, 65 insertions, 0 deletions
diff --git a/bootblocks/com_bcc.s b/bootblocks/com_bcc.s new file mode 100644 index 0000000..26daff3 --- /dev/null +++ b/bootblocks/com_bcc.s @@ -0,0 +1,65 @@ + +! This header assumes only that we're loaded at a 16 byte boundry + +ENDOFF=4 ! If you add code adjust this till it stops failing. + +org 0 +entry start +public start +start: + call chk ! This chunk allows this code to exist at _any_ click +chk: + pop ax + mov cl,#4 + shr ax,cl + mov bx,cs + add ax,bx + push ax + mov bx,#going + push bx + retf +going: + mov ds,ax + + add ax,#ENDOFF+2 ! New CS + mov bx,ax ! Saved + mov dx,[a_entry] ! Save the entry - zero + mov ax,[btype] + and ax,#$20 ! Split I/D ? + jz impure + mov cl,#4 + mov ax,[a_text] + shr ax,cl +impure: ! ax is now offset 'tween CS&DS + add ax,bx ! ax = DS + mov ss,ax + mov sp,[a_total] ! SS:SP is now ready for prog. + mov ds,ax + xor cx,cx ! argc, argv and envp = 0 + push cx + push cx + push cx + push bx ! CS + push dx ! Entry address + retf ! Gone. + +! Check for overlap +end_of_code: + if end_of_code>hitme + fail + endif + +.org ((ENDOFF)<<4)-1 +hitme: +.byte 0xFF ! Marker + +magic: .space 2 ! A.out header +btype: .space 2 +headerlen: .space 4 +a_text: .space 4 +a_data: .space 4 +a_bss: .space 4 +a_entry: .space 4 +a_total: .space 4 +a_syms: .space 4 +.org (ENDOFF+2)<<4 ! Code start. |