diff options
Diffstat (limited to 'rllpack.inc')
| -rw-r--r-- | rllpack.inc | 86 |
1 files changed, 50 insertions, 36 deletions
diff --git a/rllpack.inc b/rllpack.inc index 0714956a..e5d1d5e5 100644 --- a/rllpack.inc +++ b/rllpack.inc @@ -1,5 +1,4 @@ -; -*- fundamental -*- -; ----------------------------------------------------------------------- +; -*- fundamental -*- --------------------------------------------------- ; ; Copyright 2004-2008 H. Peter Anvin - All Rights Reserved ; @@ -22,29 +21,37 @@ ; 129-255 = (x-126) times subsequent byte ; 0 = end of data ; +; These structures are stored *in reverse order* in high memory. +; High memory pointers point to one byte beyond the end. +; section .text ; ; rllpack: -; Pack CX bytes from DS:SI into ES:DI -; Returns updated SI, DI and CX = number of bytes output +; Pack CX bytes from SI into EDI. +; Returns updated SI and EDI. ; rllpack: - push ax - push bx + push word .pmentry + call simple_pm_call + ret + +.pmentry: push cx - push bp - push di + push ebx + push edx .startseq: xor ax,ax ; Zero byte - xor bx,bx ; Run length zero - mov bp,di ; Pointer to header byte - stosb ; Store header byte (might be zero) + xor ebx,ebx ; Run length zero + dec edi + mov edx,edi ; Pointer to header byte + mov [edi],al jcxz .done_null .stdbyte: lodsb - stosb + dec edi + mov [edi],al dec cx cmp ah,al je .same @@ -53,7 +60,7 @@ rllpack: xor bx,bx .plainbyte: inc bx - inc byte [es:bp] + inc byte [edx] jcxz .done jns .stdbyte jmp .startseq @@ -61,18 +68,20 @@ rllpack: cmp bl,2 jb .plainbyte ; 3 bytes or more in a row, time to convert sequence - sub byte [es:bp],bl + sub [edx],bl jnz .normal - dec di ; We killed a whole stretch, remove start byte + inc edi ; We killed a whole stretch, + ; drop start byte .normal: inc bx - sub di,bx - mov bp,di + add edi,ebx mov al,bl add al,126 - stosb - mov al,ah - stosb + dec edi + mov edx,edi + mov [edi],al + dec edi + mov [edi],ah .getrun: jcxz .done cmp bl,255-126 @@ -81,52 +90,57 @@ rllpack: cmp al,ah jne .nomatch inc bx - inc byte [es:bp] + inc byte [edx] dec cx jmp .getrun .nomatch: dec si jmp .startseq .done: - xor al,al - stosb + dec edi + mov [edi],cl ; CX = 0 here .done_null: - pop dx - sub dx,di - neg dx - pop bp + pop edx + pop ebx pop cx - pop bx - pop ax ret ; ; rllunpack: -; Unpack bytes from DS:SI into ES:DI -; On return SI, DI are updated and CX contains number of bytes output +; Unpack bytes from ESI into DI +; On return ESI, DI are updated and CX contains number of bytes output. ; rllunpack: - push ax + push word .pmentry + call simple_pm_call + ret + +.pmentry: push di xor cx,cx .header: - lodsb + dec esi + mov al,[esi] and al,al jz .done cmp al,129 jae .isrun ; Not a run mov cl,al - rep movsb +.copy: + dec esi + mov al,[esi] + stosb + loop .copy jmp .header .isrun: sub al,126 mov cl,al - lodsb + dec esi + mov al,[esi] rep stosb jmp .header .done: pop cx sub cx,di neg cx - pop ax ret |