Initial import

1 files changed, 235 insertions, 0 deletions

diff --git a/src/vga.c b/src/vga.c
new file mode 100644
index 0000000..a9f5a18
--- /dev/null
+++ b/src/vga.c
@@ -0,0 +1,235 @@
+#include <stdlib.h>
+#include <string.h>
+#include <stdint.h>
+#include <dpmi.h>
+#include <sys/nearptr.h>
+#include <pc.h>
+#include <dos.h>
+
+#include "ubox_vga.h"
+
+static uint8_t buffer[320 * 200];
+static uint8_t *screen = NULL;
+static uint8_t *target = NULL;
+
+uint8_t ubox_open_framebuffer()
+{
+    if (__djgpp_nearptr_enable() == 0)
+        return 0;
+
+    target = screen = (uint8_t *)(0xa0000 + __djgpp_conventional_base);
+    return 1;
+}
+
+void ubox_blit_target(uint8_t t)
+{
+    target = t ? buffer : screen;
+}
+
+void ubox_close_framebuffer()
+{
+    __djgpp_nearptr_disable();
+}
+
+uint8_t ubox_set_mode(uint8_t mode)
+{
+    __dpmi_regs regs = { 0 };
+
+    /* detect VGA card */
+    regs.x.ax = 0x1a00;
+    __dpmi_int(0x10, &regs);
+    if (regs.h.al != 0x1a)
+        return 0;
+
+    memset(&regs, 0, sizeof(regs));
+    regs.x.ax = mode;
+    __dpmi_int(0x10, &regs);
+
+    if (mode == 0x13)
+    {
+        /* setup the VGA: 320x200 @ 60Hz */
+        /* from: https://gist.github.com/juj/34306e6da02a8a7043e393f01e013f24 */
+        disable();
+
+        /* XXX: probably not neeed */
+        ubox_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 */
+        ubox_wait_vsync();
+
+        outportw(0x3d4, 0x2813); /* 8 pixel chars */
+        outportw(0x3d4, 0x8e11); /* restore retrace */
+        enable();
+    }
+
+    return 1;
+}
+
+void ubox_wait_vsync()
+{
+    while (inportb(0x3da) & 8);
+    while (!(inportb(0x3da) & 8));
+}
+
+void ubox_wait_frames(uint16_t frames)
+{
+    /* wait some time */
+    while (frames--)
+        ubox_wait_vsync();
+}
+
+void ubox_set_palette(const uint8_t *palette)
+{
+    outportb(0x3c8, 0);
+    for (int i = 0; i < 768; i++)
+        outportb(0x3c9, palette[i] >> 2);
+}
+
+void ubox_blit(const uint8_t *sprite, const ubox_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 == UBOX_TRANSPARENT)
+            {
+                dtarget++;
+                continue;
+            }
+
+            *dtarget++ = b;
+        }
+        dtarget += inc;
+    }
+}
+
+void ubox_blit_c(const uint8_t *sprite, const ubox_rect *dst, uint8_t c)
+{
+    uint8_t *dtarget = target + dst->x + dst->y * 320;
+
+    asm volatile (
+        "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 blitrc_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"
+        : /*no output */
+        : "S" (sprite), "D" (dtarget),
+        "b" ((uint32_t)dst->h), "d" ((uint32_t)c),
+        "c" ((uint32_t)dst->w), "i" (UBOX_TRANSPARENT)
+        : "eax", "ebp"
+    );
+}
+
+void ubox_blitrc(const uint8_t *sprite, const ubox_rect *src, const ubox_rect *dst)
+{
+    uint8_t *dtarget = target + dst->x + dst->y * 320;
+
+    sprite += src->x + src->y * src->w;
+
+    asm volatile (
+        "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"
+        : /*no output */
+        : "S" (sprite), "D" (dtarget),
+        "b" ((uint32_t)dst->h), "d" ((uint32_t)(src->w - dst->w)),
+        "c" ((uint32_t)dst->w), "i" (UBOX_TRANSPARENT)
+        : "eax", "ebp"
+    );
+}
+
+void ubox_blit_erase(uint8_t c)
+{
+    memset(target, c, 320 * 200);
+}
+
+void ubox_blit_copy_all()
+{
+    memcpy(screen, buffer, 320 * 200);
+}
+
+void ubox_blit_copy(const ubox_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 ubox_blit_copy16(const ubox_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"
+    );
+}