azrp: first version of text shader (slow!), based on topti-cg

azur/CMakeLists.txt

@@ -75,7 +75,10 @@ if(AZUR_GRAPHICS_GINT_CG)
     src/gint/shaders/triangle.S
     # Rectangle shader
     src/gint/shaders/rect.c
-    src/gint/shaders/rect.S)
+    src/gint/shaders/rect.S
+    # Text shader
+    src/gint/shaders/text.c
+    src/gint/shaders/text.S)
 endif()
 
 add_library(azur STATIC ${SOURCES})

azur/include/azur/gint/render.h

@@ -239,6 +239,14 @@ enum {
     AZRP_RECT_WHITEN = -3,
 };
 
+/* azrp_text(): Render a string of text, like dtext(). */
+void azrp_text(int x, int y, font_t const *f, char const *str, int fg,
+    int size);
+
+/* azrp_text_opt(): Render text with options similar to dtext_opt(). */
+void azrp_text_opt(int x, int y, font_t const *font, int fg, int halign,
+    int valign, char const *str, int size);
+
 //---
 // Performance indicators
 //

azur/src/gint/shaders/rect.c

@@ -1,6 +1,6 @@
 #include <azur/gint/render.h>
 
-uint AZRP_SHADER_RECT = -1;
+uint8_t AZRP_SHADER_RECT = -1;
 
 static void configure(void)
 {

azur/src/gint/shaders/text.S

@@ -0,0 +1,83 @@
+.global _azrp_text_glyph
+
+/* Naive glyph rendering. Possible optimizations:
+   - Use a 1-bit bitmask instead of a longword index? */
+
+/* Parameters:
+    r4:        fragment
+    r5:        data
+    r6:        color
+    r7:        height
+    @(4,r15):  width
+    @(8,r15):  dataw - width (stride)
+    @(12,r15): starting index in data
+   Stack:
+    @(0,r15): r8 save
+
+   Register allocation:
+    r0: (temporary)
+    r1: (temporary)
+    r2: x counter
+    r3: glyph data index
+    r4: fragment pointer
+    r5: glyph pointer
+    r6: color
+    r7: y counter
+   Callee-saved registers:
+   r8: fragment stride */
+
+_azrp_text_glyph:
+
+	/* Compute fragment stride: 2 * (azrp_width-width) */
+	mov.l	r8, @-r15
+	mov.l	1f, r8
+	mov.l	@r8, r8
+	mov.l	@(4, r15), r3
+	sub	r3, r8
+	shll	r8
+
+	/* Load the starting index */
+	mov.l	@(12, r15), r3
+
+.fg_y:
+	/* Initialize width counter */
+	mov.l	@(4, r15), r2
+
+.fg_x:
+	/* Load one bit of data in T */
+	mov	r3, r0
+	mov	#-5, r1
+	shld	r1, r0
+	shll2	r0
+	mov.l	@(r0, r5), r1
+
+	mov	r3, r0
+	and	#31, r0
+
+	shld	r0, r1
+	shll	r1
+
+	/* Write color to fragment only if it's a 1 bit */
+	bf	.fg_next
+	mov.w	r6, @r4
+
+.fg_next:
+	/* Leave the x-loop if x counter reaches 0 */
+	add	#2, r4
+	dt	r2
+	bf/s	.fg_x
+	add	#1, r3
+
+	/* Move to next row, leave the y-loop if height reaches 0 */
+	dt	r7
+	mov.l	@(8, r15), r0
+	add	r0, r3
+	bf/s	.fg_y
+	add	r8, r4
+
+	rts
+	mov.l	@r15+, r8
+
+.align 4
+
+1:	.long	_azrp_width

azur/src/gint/shaders/text.c

@@ -0,0 +1,165 @@
+#include <azur/gint/render.h>
+#include <gint/defs/util.h>
+#include <gint/display.h>
+#include <string.h>
+
+uint8_t AZRP_SHADER_TEXT = -1;
+
+__attribute__((constructor))
+static void register_shader(void)
+{
+    extern azrp_shader_t azrp_shader_text;
+    AZRP_SHADER_TEXT = azrp_register_shader(azrp_shader_text, NULL);
+}
+
+//---
+
+/* This version of the text shader is a very rough adaptation of dtext(). It
+   should be optimized in several important ways in the future:
+   1. Use left-shifting in azrp_text_glyph(), which is probably faster both for
+      partial and full glyphs.
+   2. Optimize the heck out of the full-width case, which is almost every
+      single call.
+   3. Precompute the set of glyphs so the list can be reused when crossing
+      fragment boundaries, the shader can be written entirely in assembler, and
+      the command can possibly be reused?
+   4. Provide noclip toplevel functions, which I believe should provide a
+      nontrivial speed boost. */
+
+void azrp_text_glyph(uint16_t *fragment, uint32_t const *data, int color,
+    int height, int width, int stride, int index);
+
+struct command {
+    uint8_t shader_id;
+    uint8_t _;
+    int16_t x, y;
+    int16_t height, top;
+    font_t const *font;
+    char const *str;
+    int fg;
+    int size;
+};
+
+void azrp_shader_text(void *uniforms0, void *cmd0, void *frag0)
+{
+    struct command *cmd = cmd0;
+    int x = cmd->x;
+    int y = cmd->y;
+    font_t const *f = cmd->font;
+    int fg = cmd->fg;
+    int size = cmd->size;
+    /* Storage height, top position within glyph */
+    int height = min(cmd->height, azrp_frag_height - y);
+    int top = cmd->top;
+
+    uint8_t const *str = (void *)cmd->str;
+    uint8_t const *str0 = str;
+
+    /* Raw glyph data */
+    uint32_t const *data = f->data;
+
+    /* Update for next fragment */
+    cmd->height -= height;
+    cmd->top += height;
+    cmd->y = 0;
+
+    /* Move to top row */
+    uint16_t *frag = (uint16_t *)frag0 + azrp_width * y;
+
+    /* Read each character from the input string */
+    while(x < azrp_window.right)
+    {
+        uint32_t code_point = dtext_utf8_next(&str);
+        if(!code_point || (size >= 0 && str - str0 > size)) break;
+
+        int glyph = dfont_glyph_index(f, code_point);
+        if(glyph < 0) continue;
+
+        int dataw = f->prop ? f->glyph_width[glyph] : f->width;
+
+        int index = dfont_glyph_offset(f, glyph);
+
+        /* Compute horizontal intersection between glyph and screen */
+
+        int width = dataw, left = 0;
+
+        if(x + dataw <= azrp_window.left)
+        {
+            x += dataw + f->char_spacing;
+            continue;
+        }
+        if(x < azrp_window.left) {
+            left = azrp_window.left - x;
+            width -= left;
+        }
+        width = min(width, azrp_window.right - x);
+
+        /* Render glyph */
+        azrp_text_glyph(frag + x + left, data + index, fg, height, width,
+            dataw - width, top * dataw + left);
+
+        x += dataw + f->char_spacing;
+    }
+}
+
+void azrp_text(int x, int y, font_t const *f, char const *str,
+    int fg, int size)
+{
+    prof_enter(azrp_perf_cmdgen);
+
+    /* Clipping */
+    if(x >= azrp_window.right || y >= azrp_window.bottom ||
+       y + f->data_height <= azrp_window.top) {
+        prof_leave(azrp_perf_cmdgen);
+        return;
+    }
+
+    int top_overflow = y - azrp_window.top;
+    int top = 0;
+    int height = f->data_height;
+
+    if(top_overflow < 0) {
+        top = -top_overflow;
+        height += top_overflow;
+        y -= top_overflow;
+    }
+    height = min(height, azrp_window.bottom - y);
+    if(height <= 0) {
+        prof_leave(azrp_perf_cmdgen);
+        return;
+    }
+
+    int frag_first, first_offset, frag_count;
+    azrp_config_get_lines(y, f->data_height,
+        &frag_first, &first_offset, &frag_count);
+
+    struct command cmd;
+    cmd.shader_id = AZRP_SHADER_TEXT;
+    cmd.x = x;
+    cmd.y = first_offset;
+    cmd.height = height;
+    cmd.top = top;
+    cmd.font = f;
+    cmd.str = str;
+    cmd.fg = fg;
+    cmd.size = size;
+
+    azrp_queue_command(&cmd, sizeof cmd, frag_first, frag_count);
+    prof_leave(azrp_perf_cmdgen);
+}
+
+void azrp_text_opt(int x, int y, font_t const *font, int fg, int halign,
+    int valign, char const *str, int size)
+{
+    if(halign != DTEXT_LEFT || valign != DTEXT_TOP) {
+        int w, h;
+        dnsize(str, size, font, &w, &h);
+
+        if(halign == DTEXT_RIGHT)  x -= w - 1;
+        if(halign == DTEXT_CENTER) x -= (w >> 1);
+        if(valign == DTEXT_BOTTOM) y -= h - 1;
+        if(valign == DTEXT_MIDDLE) y -= (h >> 1);
+    }
+
+    azrp_text(x, y, font, str, fg, size);
+}