# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1541881809 -3600
# Node ID 6934a0847aed083294463c715537a47863e6bf7a
# Parent  ed2641a2294d143c80e20878d939fdad6ce16cc7
Simplified display configuration initialisation.

diff -r ed2641a2294d -r 6934a0847aed examples/vga/main.c
--- a/examples/vga/main.c	Sat Nov 10 19:20:13 2018 +0100
+++ b/examples/vga/main.c	Sat Nov 10 21:30:09 2018 +0100
@@ -31,8 +31,8 @@
 /* Specific functionality. */
 
 #include "devconfig.h"
-#include "display_config.h"
 #include "main.h"
+#include "vga.h"
 
 
 
@@ -87,13 +87,9 @@
 
 
 
-/* Framebuffer memory. */
-
-static uint8_t framebuffer[FRAME_SIZE * FRAME_COUNT];
+/* Initialise memory for a multi-frame display. */
 
-/* Screen start values for each frame. */
-
-uint8_t *screen_starts[FRAME_COUNT];
+static Display(display_config, LINE_LENGTH, LINE_COUNT, FRAME_COUNT);
 
 
 
@@ -347,10 +343,9 @@
     uart_init(1, FPB, 115200);
     uart_on(1);
 
-    /* Initialise memory for a double-buffered display. */
+    /* Set the display to a well-defined state. */
 
-    init_display(&display_config, framebuffer, LINE_LENGTH, LINE_COUNT,
-                 FRAME_COUNT, screen_starts);
+    init_display(&display_config);
 
     /* Initialise VGA output with one or two line channels, configuring a line
        timer and any transfer timer, with an initiating channel being introduced
diff -r ed2641a2294d -r 6934a0847aed include/display.h
--- a/include/display.h	Sat Nov 10 19:20:13 2018 +0100
+++ b/include/display.h	Sat Nov 10 21:30:09 2018 +0100
@@ -94,11 +94,39 @@
 
 
 
+/* Initialise a display. */
+
+#define Display(NAME, WIDTH, HEIGHT, FRAMES)                            \
+    uint8_t __##NAME##_framebuffer[(WIDTH) * (HEIGHT + 1) * (FRAMES)];  \
+    uint8_t *__##NAME##_screen_starts[FRAMES];                          \
+    display_config_t NAME = {                                           \
+        .framebuffer=__##NAME##_framebuffer,                            \
+        .screen_starts=__##NAME##_screen_starts,                        \
+                                                                        \
+        .line_length=WIDTH,                                             \
+        .line_count=HEIGHT,                                             \
+        .screen_size=(WIDTH) * (HEIGHT),                                \
+        .total_lines=(HEIGHT + 1) * (FRAMES),                           \
+        .frame=0,                                                       \
+        .frames=FRAMES,                                                 \
+        .max_frames=FRAMES,                                             \
+                                                                        \
+        .scanlines = SCANLINES,                                         \
+        .line_channels = LINE_CHANNELS,                                 \
+        .cell_size = CELL_SIZE,                                         \
+        .transfer_cell_size = TRANSFER_CELL_SIZE,                       \
+                                                                        \
+        .hfreq_limit = HFREQ_LIMIT,                                     \
+        .hsync_start = HSYNC_START,                                     \
+        .hsync_end = HSYNC_END,                                         \
+        .visible_start = VISIBLE_START,                                 \
+        .vfp_start = VFP_START,                                         \
+        .vsync_start = VSYNC_START,                                     \
+        .vsync_end = VSYNC_END};
+
 /* Configuration functions. */
 
-void init_display(display_config_t *cfg, uint8_t *framebuffer,
-                  uint32_t line_length, uint32_t line_count,
-                  int frames, uint8_t **screen_starts);
+void init_display(display_config_t *cfg);
 
 void init_display_properties(display_config_t *cfg);
 
diff -r ed2641a2294d -r 6934a0847aed include/vga_common.h
--- a/include/vga_common.h	Sat Nov 10 19:20:13 2018 +0100
+++ b/include/vga_common.h	Sat Nov 10 21:30:09 2018 +0100
@@ -40,4 +40,21 @@
 
 #define VSYNC_END               622
 
+/* Define DMA channels if not indicated in the build configuration. */
+
+/* CPU-based transfers: no channels. */
+
+#ifdef TRANSFER_CPU
+#define LINE_CHANNELS   0
+
+/* DMA-based transfers: single channel by default. */
+
+#else
+
+#ifndef LINE_CHANNELS
+#define LINE_CHANNELS   1
+#endif
+
+#endif /* TRANSFER_CPU */
+
 #endif /* __VGA_COMMON_H__ */
diff -r ed2641a2294d -r 6934a0847aed lib/display.c
--- a/lib/display.c	Sat Nov 10 19:20:13 2018 +0100
+++ b/lib/display.c	Sat Nov 10 21:30:09 2018 +0100
@@ -24,35 +24,8 @@
 
 /* Initialise a display configuration. */
 
-void init_display(display_config_t *cfg, uint8_t *framebuffer,
-                  uint32_t line_length, uint32_t line_count,
-                  int frames, uint8_t **screen_starts)
+void init_display(display_config_t *cfg)
 {
-    /* Framebuffer address. */
-
-    cfg->framebuffer = framebuffer;
-
-    /* Frame allocation limits. */
-
-    cfg->total_lines = (line_count + 1) * frames;
-    cfg->max_frames = frames;
-
-    /* Screen size and dimensions. */
-
-    cfg->screen_size = line_length * line_count;
-    cfg->line_length = line_length;
-    cfg->line_count = line_count;
-
-    /* Set the number of frames and the current frame. */
-
-    cfg->frames = frames;
-    cfg->frame = 0;
-
-    /* Set the pointer to a collection of screen start pointers, one per
-       frame. */
-
-    cfg->screen_starts = screen_starts;
-
     init_frames(cfg);
     init_display_properties(cfg);
 }