commit aa94925d296dc31a38360056227ffb0eea749572
author Kevin O'Connor <kevin@koconnor.net> Sun Mar 31 22:59:06 2024 -0400
committer Kevin O'Connor <kevin@koconnor.net> Fri Apr 05 17:59:42 2024 -0400
tree 15ac0ca77c436968f546297d3fe6430d0495a1e7
parent 8de51a5af213ffd2981876dea737b65be75b1488

stdvga: Rework stdvga palette index paging interface functions

Rename the functions to make them a little easier to understand.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

vgasrc/stdvga.c

diff --git a/vgasrc/stdvga.c b/vgasrc/stdvga.c
index 63700d4..4e2fb1f 100644
--- a/vgasrc/stdvga.c
+++ b/vgasrc/stdvga.c
@@ -91,31 +91,36 @@
     stdvga_attr_mask(0x10, 0x08, (enable_blink & 0x01) << 3);
 }
 
+// Select 4-bit or 6-bit palette indexes (for "page" switching of colors)
 void
-stdvga_select_video_dac_color_page(u8 flag, u8 data)
+stdvga_set_palette_pagesize(u8 pal_pagesize)
 {
-    if (!(flag & 0x01)) {
-        // select paging mode
-        stdvga_attr_mask(0x10, 0x80, data << 7);
-        return;
-    }
-    // select page
-    u8 val = stdvga_attr_read(0x10);
-    if (!(val & 0x80))
-        data <<= 2;
-    data &= 0x0f;
-    stdvga_attr_write(0x14, data);
+    stdvga_attr_mask(0x10, 0x80, pal_pagesize << 7);
 }
 
+// Set palette index offset (enables color switching via "pages")
 void
-stdvga_read_video_dac_state(u8 *pmode, u8 *curpage)
+stdvga_set_palette_page(u8 pal_page)
+{
+    // Check if using 4-bit or 6-bit "palette index pages"
+    u8 val = stdvga_attr_read(0x10);
+    if (!(val & 0x80))
+        pal_page <<= 2;
+    // select page
+    pal_page &= 0x0f;
+    stdvga_attr_write(0x14, pal_page);
+}
+
+// Report current palette index pagesize and current page
+void
+stdvga_get_palette_page(u8 *pal_pagesize, u8 *pal_page)
 {
     u8 val1 = stdvga_attr_read(0x10) >> 7;
     u8 val2 = stdvga_attr_read(0x14) & 0x0f;
     if (!(val1 & 0x01))
         val2 >>= 2;
-    *pmode = val1;
-    *curpage = val2;
+    *pal_pagesize = val1;
+    *pal_page = val2;
 }
 
 

vgasrc/stdvga.h

diff --git a/vgasrc/stdvga.h b/vgasrc/stdvga.h
index 6ce6a90..e9cd2f0 100644
--- a/vgasrc/stdvga.h
+++ b/vgasrc/stdvga.h
@@ -52,8 +52,9 @@
 void stdvga_set_all_palette_reg(u16 seg, u8 *data_far);
 void stdvga_get_all_palette_reg(u16 seg, u8 *data_far);
 void stdvga_set_palette_blinking(u8 enable_blink);
-void stdvga_select_video_dac_color_page(u8 flag, u8 data);
-void stdvga_read_video_dac_state(u8 *pmode, u8 *curpage);
+void stdvga_set_palette_pagesize(u8 pal_pagesize);
+void stdvga_set_palette_page(u8 pal_page);
+void stdvga_get_palette_page(u8 *pal_pagesize, u8 *pal_page);
 void stdvga_perform_gray_scale_summing(u16 start, u16 count);
 void stdvga_set_text_block_specifier(u8 spec);
 void stdvga_planar4_plane(int plane);

vgasrc/vgabios.c

diff --git a/vgasrc/vgabios.c b/vgasrc/vgabios.c
index b55a4db..00325f5 100644
--- a/vgasrc/vgabios.c
+++ b/vgasrc/vgabios.c
@@ -583,7 +583,10 @@
 static void
 handle_101013(struct bregs *regs)
 {
-    stdvga_select_video_dac_color_page(regs->bl, regs->bh);
+    if (!(regs->bl & 0x01))
+        stdvga_set_palette_pagesize(regs->bh);
+    else
+        stdvga_set_palette_page(regs->bh);
 }
 
 static void noinline
@@ -617,7 +620,7 @@
 static void
 handle_10101a(struct bregs *regs)
 {
-    stdvga_read_video_dac_state(&regs->bl, &regs->bh);
+    stdvga_get_palette_page(&regs->bl, &regs->bh);
 }
 
 static void