Old crc16 is now a .asm

This commit is contained in:
2025-10-06 22:40:10 +02:00
parent 0917aa1280
commit ec3fe0e07d
2 changed files with 45 additions and 57 deletions

45
src/crc16.asm Normal file
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@@ -0,0 +1,45 @@
CPU 8086
_start:
push bp
mov bp, sp
mov si, [bp+8]
push word [si]
mov si, [bp+10]
push word [si]
call crc16
mov di, [bp+6]
mov [di], ax
mov sp, bp
pop bp
retf 6
crc16:
push bp
mov bp, sp
mov bx, [bp+4]
add [bp+6], bx
mov ax, -1
.L2:
cmp bx, [bp+6]
jne .L5
pop bp
ret
.L5:
mov dl, [bx]
mov cl, 0x8
shl dx, cl
xor ax, dx
mov dl, cl
.L4:
mov cx, ax
shl cx, 1
test ax, ax
xchg cx, ax
jge .L3
xor ax, 4129
.L3:
dec dl
jne .L4
inc bx
jmp .L2

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@@ -1,57 +0,0 @@
.arch i8086,jumps
.code16
.att_syntax prefix
#NO_APP
#APP
.section .text.init
.global _start
_start:
.section .text.main
.global main
main:
push %bp
mov %sp, %bp
mov 8(%bp), %si
push (%si)
call crc16
add $0x2, %sp
mov 6(%bp), %di
mov %ax, (%di)
pop %bp
lret $4
#NO_APP
.text
.global crc16
.type crc16, @function
crc16:
pushw %bp
movw %sp, %bp
xorw %bx, %bx
movw $-1, %ax
.L2:
cmpw 4(%bp), %bx
jne .L5
popw %bp
ret
.L5:
movb %cs:(%bx), %dl
movb $8, %cl
shlw %cl, %dx
xorw %dx, %ax
movb %cl, %dl
.L4:
movw %ax, %cx
shlw $1, %cx
testw %ax, %ax
xchgw %ax, %cx
jge .L3
xorw $4129, %ax
.L3:
decb %dl
jne .L4
incw %bx
jmp .L2
.size crc16, .-crc16
.ident "GCC: (GNU) 6.3.0"