Alvin G. support

README.md

@@ -18,6 +18,7 @@ Since not any consumer (especially the Raspberry Pi) can act as an SPI slave thi
 * Stern SPIKE 1 -> 128x32
 * Capcom -> 128x32
 * Gottlieb/Premier -> 128x32
+* Alvin G. & Co -> 128x32
 
 ## Reading data
 

src/dmd_interface.h

@@ -8,6 +8,7 @@
 #include "dmd_interface_sam.pio.h"
 #include "dmd_interface_spike.pio.h"
 #endif
+#include "dmd_interface_alving.pio.h"
 #include "dmd_interface_capcom.pio.h"
 #include "dmd_interface_capcom_hd.pio.h"
 #include "dmd_interface_desega.pio.h"

src/dmd_interface_alving.pio

@@ -0,0 +1,56 @@
+.define DE 7
+.define RDATA 6
+.define RCLK 5
+.define COLLAT 4
+.define DOTCLK 3
+.define SDATA 2
+.define FRAME_START_IRQ 5
+
+.program dmd_reader_alving
+    ; initialize y with 16383, number of pixels (128x32x4) - 1 because counting starts at 0.
+    set x, 31          ; x = 31 (max 5-bit value)
+    in x, 5            ; shift in 5 bits, isr = 31
+    set x, 31          ; x = 31
+    in x, 5            ; shift in 5 bits, isr = 1023
+    set x, 15          ; x = 15
+    in x, 4            ; shift in 4 bits, isr = 16383
+    mov y, isr         ; y = 16383
+
+.wrap_target
+    mov x, y           ; load number of pixels
+    mov isr, null      ; clear ISR and reset shift counter
+
+    irq clear FRAME_START_IRQ
+    wait irq FRAME_START_IRQ
+
+dotloop:
+    wait 0 gpio DOTCLK  ; falling edge
+    in null, 3          ; left padding with 3 zeros
+    wait 1 gpio DOTCLK  ; raising edge
+    in pins 1           ; read pin data
+    jmp x-- dotloop
+.wrap
+
+; Frame detection program runs in parallel to the reader program and signals the start of a new frame using an IRQ.
+.program dmd_framedetect_alving
+    wait 0 gpio RDATA
+    wait 1 gpio RDATA
+; When RDATA turned HIGH, we already missed the start of the first row, so we skip 32 end of rows before sending the first IRQ.
+; Alvin G needs to skip 3 COLLAT edges right after for a correct starting point.
+.wrap_target
+    set x, 31          ; 32 rows
+    set y, 2           ; 3 COLLAT edges
+
+rclk_loop:
+    wait 0 gpio RCLK
+    wait 1 gpio RCLK
+    jmp x-- rclk_loop
+
+collat_loop:
+    wait 0 gpio COLLAT
+    wait 1 gpio COLLAT
+    jmp y-- collat_loop
+
+    irq FRAME_START_IRQ
+.wrap
+

src/dmdreader.cpp

@@ -76,6 +76,7 @@ enum DmdType {
   DMD_DESEGA,
   DMD_SEGA_HD,
   DMD_GOTTLIEB,
+  DMD_ALVING,
   // CAPCOM need to be the last entries:
   DMD_CAPCOM,
   DMD_CAPCOM_HD,
@@ -375,6 +376,11 @@ DmdType detect_dmd() {
              (de < 13100) && (rdata > 370) && (rdata < 410)) {
     return DMD_GOTTLIEB;
 
+    // Alvin G -> DOTCLK: 1192000 | DE: 9400 | RDATA: 73
+  } else if ((dotclk > 1150000) && (dotclk < 1250000) && (de > 9200) &&
+             (de < 9600) && (rdata > 65) && (rdata < 80)) {
+    return DMD_ALVING;
+
     // Capcom -> DOTCLK: 4168000 | DE: 16280 | RDATA: 510
   } else if ((dotclk > 4000000) && (dotclk < 4300000) && (de > 16000) &&
              (de < 16500) && (rdata > 490) && (rdata < 530)) {
@@ -628,17 +634,32 @@ void dmd_dma_handler() {
       src4 = src3 + source_dwordsperline;
       uint32_t v;
 
-      for (int l = 0; l < source_height; l++) {
-        for (int w = 0; w < source_dwordsperline; w++) {
-          // On SAM line order is really messed up :-(
-          v = src4[w] * 8 + src3[w] * 1 + src2[w] * 4 + src1[w] * 2;
-          dst[w] = v;
+      if (dmd_type == DMD_SAM) {
+        for (int l = 0; l < source_height; l++) {
+          for (int w = 0; w < source_dwordsperline; w++) {
+            // On SAM line order is really messed up :-(
+            v = src4[w] * 8 + src3[w] * 1 + src2[w] * 4 + src1[w] * 2;
+            dst[w] = v;
+          }
+          src1 += source_dwordsperline * 4;  // source skips 4 lines forward
+          src2 += source_dwordsperline * 4;
+          src3 += source_dwordsperline * 4;
+          src4 += source_dwordsperline * 4;
+          dst += source_dwordsperline;  // destination skips only one line
+        }
+      } else { // Alvin G
+        for (int l = 0; l < source_height; l++) {
+          for (int w = 0; w < source_dwordsperline; w++) {
+            // First row captured counts as intensity level 3 <--
+            v = src4[w] * 4 + src3[w] * 4 + src2[w] * 4 + src1[w] * 3;
+            dst[w] = v;
+          }
+          src1 += source_dwordsperline * 4;  // source skips 4 lines forward
+          src2 += source_dwordsperline * 4;
+          src3 += source_dwordsperline * 4;
+          src4 += source_dwordsperline * 4;
+          dst += source_dwordsperline;  // destination skips only one line
         }
-        src1 += source_dwordsperline * 4;  // source skips 4 lines forward
-        src2 += source_dwordsperline * 4;
-        src3 += source_dwordsperline * 4;
-        src4 += source_dwordsperline * 4;
-        dst += source_dwordsperline;  // destination skips only one line
       }
     }
   }
@@ -849,13 +870,32 @@ void dmdreader_init() {
       break;
     }
 
+    case DMD_ALVING: {
+      uint input_pins[] = {RDATA, RCLK, COLLAT};
+      dmdreader_programs_init(
+          &dmd_reader_alving_program,
+          dmd_reader_alving_program_get_default_config,
+          &dmd_framedetect_alving_program,
+          dmd_framedetect_alving_program_get_default_config, input_pins, 2, 0);
+
+      source_width = 128;
+      source_height = 32;
+      source_bitsperpixel = 4;
+      target_bitsperpixel = 4;
+      source_planesperframe = 1;  // in Alvin G there is one plane
+      // with 4x line oversampling
+      source_lineoversampling = LINEOVERSAMPLING_4X;
+      source_mergeplanes = MERGEPLANES_NONE;
+      break;
+    }
+
     case DMD_CAPCOM: {
       uint input_pins[] = {RDATA, RCLK};
       dmdreader_programs_init(&dmd_reader_capcom_program,
                               dmd_reader_capcom_program_get_default_config,
                               &dmd_framedetect_capcom_program,
                               dmd_framedetect_capcom_program_get_default_config,
-                              input_pins, 2, 0);
+                              input_pins, 3, 0);
 
       source_width = 128;
       source_height = 32;