d_copy.s

//
// d_copy.s
// x86 assembly-language screen copying code.
//

#include "asm_i386.h"
#include "quakeasm.h"
#include "asm_draw.h"

    .data

LCopyWidth:     .long   0
LBlockSrcStep:  .long   0
LBlockDestStep: .long   0
LSrcDelta:      .long   0
LDestDelta:     .long   0

#define bufptr  4+16

// copies 16 rows per plane at a pop; idea is that 16*512 = 8k, and since
// no Mode X mode is wider than 360, all the data should fit in the cache for
// the passes for the next 3 planes

    .text

.globl C(VGA_UpdatePlanarScreen)
C(VGA_UpdatePlanarScreen):
    pushl   %ebp                // preserve caller's stack frame
    pushl   %edi
    pushl   %esi                // preserve register variables
    pushl   %ebx

    movl    C(VGA_bufferrowbytes),%eax
    shll    $1,%eax
    movl    %eax,LBlockSrcStep
    movl    C(VGA_rowbytes),%eax
    shll    $1,%eax
    movl    %eax,LBlockDestStep

    movl    $0x3C4,%edx
    movb    $2,%al
    outb    %al,%dx     // point the SC to the Map Mask
    incl    %edx

    movl    bufptr(%esp),%esi
    movl    C(VGA_pagebase),%edi
    movl    C(VGA_height),%ebp
    shrl    $1,%ebp

    movl    C(VGA_width),%ecx
    movl    C(VGA_bufferrowbytes),%eax
    subl    %ecx,%eax
    movl    %eax,LSrcDelta
    movl    C(VGA_rowbytes),%eax
    shll    $2,%eax
    subl    %ecx,%eax
    movl    %eax,LDestDelta
    shrl    $4,%ecx
    movl    %ecx,LCopyWidth

LRowLoop:
    movb    $1,%al

LPlaneLoop:
    outb    %al,%dx
    movb    $2,%ah

    pushl   %esi
    pushl   %edi
LRowSetLoop:
    movl    LCopyWidth,%ecx
LColumnLoop:
    movb    12(%esi),%bh
    movb    8(%esi),%bl
    shll    $16,%ebx
    movb    4(%esi),%bh
    movb    (%esi),%bl
    movl    %ebx,(%edi)
    addl    $16,%esi
    addl    $4,%edi
    decl    %ecx
    jnz     LColumnLoop

    addl    LDestDelta,%edi
    addl    LSrcDelta,%esi
    decb    %ah
    jnz     LRowSetLoop

    popl    %edi
    popl    %esi
    incl    %esi

    shlb    $1,%al
    cmpb    $16,%al
    jnz     LPlaneLoop

    subl    $4,%esi
    addl    LBlockSrcStep,%esi
    addl    LBlockDestStep,%edi
    decl    %ebp
    jnz     LRowLoop

    popl    %ebx                // restore register variables
    popl    %esi
    popl    %edi
    popl    %ebp                // restore the caller's stack frame

    ret


#define srcptr          4+16
#define destptr         8+16
#define width           12+16
#define height          16+16
#define srcrowbytes     20+16
#define destrowbytes    24+16

.globl C(VGA_UpdateLinearScreen)
C(VGA_UpdateLinearScreen):
    pushl   %ebp                // preserve caller's stack frame
    pushl   %edi
    pushl   %esi                // preserve register variables
    pushl   %ebx

    cld
    movl    srcptr(%esp),%esi
    movl    destptr(%esp),%edi
    movl    width(%esp),%ebx
    movl    srcrowbytes(%esp),%eax
    subl    %ebx,%eax
    movl    destrowbytes(%esp),%edx
    subl    %ebx,%edx
    shrl    $2,%ebx
    movl    height(%esp),%ebp
LLRowLoop:
    movl    %ebx,%ecx
    rep/movsl   (%esi),(%edi)
    addl    %eax,%esi
    addl    %edx,%edi
    decl    %ebp
    jnz     LLRowLoop

    popl    %ebx                // restore register variables
    popl    %esi
    popl    %edi
    popl    %ebp                // restore the caller's stack frame

    ret