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#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <dpmi.h>
#include <sys/nearptr.h>
#include <pc.h>
#include <dos.h>
#include "vga.h"
static uint8_t buffer[320 * 200];
static uint8_t *screen = NULL;
static uint8_t *target = NULL;
uint8_t open_framebuffer()
{
if (__djgpp_nearptr_enable() == 0)
return 0;
target = screen = (uint8_t *)(0xa0000 + __djgpp_conventional_base);
return 1;
}
void blit_target(uint8_t t)
{
target = t ? buffer : screen;
}
void close_framebuffer()
{
__djgpp_nearptr_disable();
}
uint8_t set_mode(uint8_t mode)
{
__dpmi_regs regs = { 0 };
/* detect VGA card */
regs.x.ax = 0x1a00;
__dpmi_int(0x10, ®s);
if (regs.h.al != 0x1a)
return 0;
memset(®s, 0, sizeof(regs));
regs.x.ax = mode;
__dpmi_int(0x10, ®s);
if (mode == 0x13)
{
/* setup the VGA: 320x200 @ 60Hz */
/* from: https://gist.github.com/juj/34306e6da02a8a7043e393f01e013f24 */
disable();
/* XXX: probably not neeed */
wait_vsync();
outportw(0x3d4, 0x0011); /* Turn off write protect to CRTC registers */
outportw(0x3d4, 0x0b06); /* New vertical total=525 lines, bits 0-7 */
outportw(0x3d4, 0x3e07); /* New vertical total=525 lines, bits 8-9 */
outportw(0x3d4, 0xb910); /* Vsync start=scanline 185 */
outportw(0x3d4, 0x8f12); /* Vertical display end=scanline 399, bits 0-7 */
outportw(0x3d4, 0xb815); /* Vertical blanking start=scanline 440, bits 0-7 */
outportw(0x3d4, 0xe216); /* Adjust vblank end position */
outportw(0x3d4, 0x8511); /* Vsync length=2 lines + turn write protect back on */
/* XXX: probably not neeed */
wait_vsync();
outportw(0x3d4, 0x2813); /* 8 pixel chars */
outportw(0x3d4, 0x8e11); /* restore retrace */
enable();
}
return 1;
}
void wait_vsync()
{
while (inportb(0x3da) & 8);
while (!(inportb(0x3da) & 8));
}
void wait_frames(uint16_t frames)
{
/* wait some time */
for (uint16_t i = 0; i < frames; i++)
wait_vsync();
}
void set_palette(const uint8_t *palette)
{
outportb(0x3c8, 0);
for (int i = 0; i < 768; i++)
outportb(0x3c9, palette[i] >> 2);
}
void blit(const uint8_t *sprite, const Rect *dst)
{
uint8_t b;
uint8_t *dtarget = target + dst->x + dst->y * 320;
const uint16_t inc = 320 - dst->w;
for (uint16_t j = dst->h; j > 0; j--)
{
for (uint16_t i = dst->w; i > 0; i--)
{
b = *sprite++;
/* transparent */
if (b == TRANSPARENT)
{
dtarget++;
continue;
}
*dtarget++ = b;
}
dtarget += inc;
}
}
void blit_c(const uint8_t *sprite, const Rect *dst, uint8_t c)
{
uint8_t *dtarget = target + dst->x + dst->y * 320;
asm volatile (
"push %%ebp\n\t"
"movl $320, %%ebp\n\t"
"subl %%ecx, %%ebp\n\t"
"blit_c_w:\n\t"
"movl %%ecx, %%eax\n\t"
"blit_c_w_loop:\n\t"
"movb (%%esi), %%ah\n\t"
"cmpb $%p5, %%ah\n\t"
"je blit_c_tr\n\t"
"orb %%ah, %%ah\n\t"
"je blit_c_store\n\t"
"movb %%dl, %%ah\n\t"
"blit_c_store:\n\t"
"movb %%ah, (%%edi)\n\t"
"blit_c_tr:\n\t"
"incl %%esi\n\t"
"incl %%edi\n\t"
"decb %%al\n\t"
"jne blit_c_w_loop\n\t"
"addl %%ebp, %%edi\n\t"
"decl %%ebx\n\t"
"jne blit_c_w\n\t"
"pop %%ebp\n\t"
: /*no output */
: "S" (sprite), "D" (dtarget),
"b" ((uint32_t)dst->h), "d" ((uint32_t)c),
"c" ((uint32_t)dst->w), "i" (TRANSPARENT)
: "eax"
);
}
void blitrc(const uint8_t *sprite, const Rect *src, const Rect *dst)
{
uint8_t *dtarget = target + dst->x + dst->y * 320;
sprite += src->x + src->y * src->w;
asm volatile (
"push %%ebp\n\t"
"movl $320, %%ebp\n\t"
"subl %%ecx, %%ebp\n\t"
"blitrc_w:\n\t"
"movl %%ecx, %%eax\n\t"
"blitrc_w_loop:\n\t"
"movb (%%esi), %%ah\n\t"
"cmpb $%p5, %%ah\n\t"
"je blitrc_tr\n\t"
"movb %%ah, (%%edi)\n\t"
"blitrc_tr:\n\t"
"incl %%esi\n\t"
"incl %%edi\n\t"
"decb %%al\n\t"
"jne blitrc_w_loop\n\t"
"addl %%edx, %%esi\n\t"
"addl %%ebp, %%edi\n\t"
"decl %%ebx\n\t"
"jne blitrc_w\n\t"
"pop %%ebp\n\t"
: /*no output */
: "S" (sprite), "D" (dtarget),
"b" ((uint32_t)dst->h), "d" ((uint32_t)(src->w - dst->w)),
"c" ((uint32_t)dst->w), "i" (TRANSPARENT)
: "eax"
);
}
void blit_erase(uint8_t c)
{
memset(target, c, 320 * 200);
}
void blit_copy_all()
{
memcpy(screen, buffer, 320 * 200);
}
void blit_copy(const Rect *dst)
{
uint8_t *src = buffer + dst->x + dst->y * 320;
uint8_t *dtarget = screen + dst->x + dst->y * 320;
for (uint16_t j = dst->h; j > 0; j--)
{
memcpy(dtarget, src, dst->w);
src += 320;
dtarget += 320;
}
}
void blit_copy16(const Rect *dst)
{
uint8_t *src = buffer + dst->x + dst->y * 320;
uint8_t *dtarget = screen + dst->x + dst->y * 320;
asm volatile (
"movl $0x130, %%ebx\n\t"
"cld\n\t"
"blit_copy16_loop:\n\t"
"movsl\n\t"
"movsl\n\t"
"movsl\n\t"
"movsl\n\t"
"addl %%ebx, %%esi\n\t"
"addl %%ebx, %%edi\n\t"
"decl %%eax\n\t"
"orl %%eax, %%eax\n\t"
"jne blit_copy16_loop\n\t"
: /* no output */
: "S" (src), "D" (dtarget), "a" ((uint32_t)dst->h)
: "ecx", "ebx"
);
}
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