Initial code and test app

.gitignore

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+CMakeLists.txt.user
+CMakeCache.txt
+CMakeFiles
+CMakeScripts
+Testing
+Makefile
+cmake_install.cmake
+install_manifest.txt
+compile_commands.json
+CTestTestfile.cmake
+_deps
+build/**

.gitmodules

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+[submodule "submodules/vrEmuTms9918"]
+	path = submodules/vrEmuTms9918
+	url = https://github.com/visrealm/vrEmuTms9918.git

.vscode/settings.json

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+{
+  "files.associations": {
+    "*.md": "markdown",
+    "xtr1common": "c"
+  }
+}

CMakeLists.txt

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+cmake_minimum_required(VERSION 3.12)
+
+# pull in PICO SDK (must be before project)
+include(pico_sdk_import.cmake)
+
+# pull in helpers for my custom tools
+include(visrealm_tools.cmake)
+
+set(BUILD_SHARED_LIBS OFF)
+
+set(PROJECT pico-prom)
+
+project(${PROJECT} C CXX)
+
+set(CMAKE_C_STANDARD 11)
+set(CMAKE_CXX_STANDARD 17)
+
+# Initialize the Pico SDK
+pico_sdk_init()
+
+add_subdirectory(src)
+add_subdirectory(test)
+add_subdirectory(submodules/vrEmuTms9918)
+

LICENSE

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+MIT License
+
+Copyright (c) 2024 Troy Schrapel
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+# PICO9918
+
+A drop-in replacement for a classic TMS9918A VDP using a Raspberry Pi Pico

pico_sdk_import.cmake

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+# This is a copy of <PICO_SDK_PATH>/external/pico_sdk_import.cmake
+
+# This can be dropped into an external project to help locate this SDK
+# It should be include()ed prior to project()
+
+if (DEFINED ENV{PICO_SDK_PATH} AND (NOT PICO_SDK_PATH))
+    set(PICO_SDK_PATH $ENV{PICO_SDK_PATH})
+    message("Using PICO_SDK_PATH from environment ('${PICO_SDK_PATH}')")
+endif ()
+
+if (DEFINED ENV{PICO_SDK_FETCH_FROM_GIT} AND (NOT PICO_SDK_FETCH_FROM_GIT))
+    set(PICO_SDK_FETCH_FROM_GIT $ENV{PICO_SDK_FETCH_FROM_GIT})
+    message("Using PICO_SDK_FETCH_FROM_GIT from environment ('${PICO_SDK_FETCH_FROM_GIT}')")
+endif ()
+
+if (DEFINED ENV{PICO_SDK_FETCH_FROM_GIT_PATH} AND (NOT PICO_SDK_FETCH_FROM_GIT_PATH))
+    set(PICO_SDK_FETCH_FROM_GIT_PATH $ENV{PICO_SDK_FETCH_FROM_GIT_PATH})
+    message("Using PICO_SDK_FETCH_FROM_GIT_PATH from environment ('${PICO_SDK_FETCH_FROM_GIT_PATH}')")
+endif ()
+
+set(PICO_SDK_PATH "${PICO_SDK_PATH}" CACHE PATH "Path to the Raspberry Pi Pico SDK")
+set(PICO_SDK_FETCH_FROM_GIT "${PICO_SDK_FETCH_FROM_GIT}" CACHE BOOL "Set to ON to fetch copy of SDK from git if not otherwise locatable")
+set(PICO_SDK_FETCH_FROM_GIT_PATH "${PICO_SDK_FETCH_FROM_GIT_PATH}" CACHE FILEPATH "location to download SDK")
+
+if (NOT PICO_SDK_PATH)
+    if (PICO_SDK_FETCH_FROM_GIT)
+        include(FetchContent)
+        set(FETCHCONTENT_BASE_DIR_SAVE ${FETCHCONTENT_BASE_DIR})
+        if (PICO_SDK_FETCH_FROM_GIT_PATH)
+            get_filename_component(FETCHCONTENT_BASE_DIR "${PICO_SDK_FETCH_FROM_GIT_PATH}" REALPATH BASE_DIR "${CMAKE_SOURCE_DIR}")
+        endif ()
+        # GIT_SUBMODULES_RECURSE was added in 3.17
+        if (${CMAKE_VERSION} VERSION_GREATER_EQUAL "3.17.0")
+            FetchContent_Declare(
+                    pico_sdk
+                    GIT_REPOSITORY https://github.com/raspberrypi/pico-sdk
+                    GIT_TAG master
+                    GIT_SUBMODULES_RECURSE FALSE
+            )
+        else ()
+            FetchContent_Declare(
+                    pico_sdk
+                    GIT_REPOSITORY https://github.com/raspberrypi/pico-sdk
+                    GIT_TAG master
+            )
+        endif ()
+
+        if (NOT pico_sdk)
+            message("Downloading Raspberry Pi Pico SDK")
+            FetchContent_Populate(pico_sdk)
+            set(PICO_SDK_PATH ${pico_sdk_SOURCE_DIR})
+        endif ()
+        set(FETCHCONTENT_BASE_DIR ${FETCHCONTENT_BASE_DIR_SAVE})
+    else ()
+        message(FATAL_ERROR
+                "SDK location was not specified. Please set PICO_SDK_PATH or set PICO_SDK_FETCH_FROM_GIT to on to fetch from git."
+                )
+    endif ()
+endif ()
+
+get_filename_component(PICO_SDK_PATH "${PICO_SDK_PATH}" REALPATH BASE_DIR "${CMAKE_BINARY_DIR}")
+if (NOT EXISTS ${PICO_SDK_PATH})
+    message(FATAL_ERROR "Directory '${PICO_SDK_PATH}' not found")
+endif ()
+
+set(PICO_SDK_INIT_CMAKE_FILE ${PICO_SDK_PATH}/pico_sdk_init.cmake)
+if (NOT EXISTS ${PICO_SDK_INIT_CMAKE_FILE})
+    message(FATAL_ERROR "Directory '${PICO_SDK_PATH}' does not appear to contain the Raspberry Pi Pico SDK")
+endif ()
+
+set(PICO_SDK_PATH ${PICO_SDK_PATH} CACHE PATH "Path to the Raspberry Pi Pico SDK" FORCE)
+
+include(${PICO_SDK_INIT_CMAKE_FILE})

src/CMakeLists.txt

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+set(PROGRAM pico9918)
+
+#add_subdirectory(pio-utils)
+
+add_executable(${PROGRAM})
+
+target_sources(${PROGRAM} PRIVATE main.c tms9918.pio.h)
+
+# generate header file from pio
+pico_generate_pio_header(${PROGRAM} ${CMAKE_CURRENT_LIST_DIR}/tms9918.pio)
+
+pico_add_extra_outputs(${PROGRAM})
+
+target_link_libraries(${PROGRAM} PUBLIC
+        pico_stdlib
+        hardware_pio
+        pico9918-vga
+        vrEmuTms9918
+        vrEmuTms9918Util)
+
+add_subdirectory(pio-utils)
+add_subdirectory(tms9918)

src/main.c

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+/*
+ * Project: pico9918
+ *
+ * Copyright (c) 2024 Troy Schrapel
+ *
+ * This code is licensed under the MIT license
+ *
+ * https://github.com/visrealm/pico-prom
+ *
+ */
+
+#include "vga.h"
+#include "vga-modes.h"
+
+#include "tms9918.pio.h"
+
+#include "vrEmuTms9918Util.h"
+
+#include "pico/stdlib.h"
+
+#include <stdlib.h>
+
+
+ /*
+  * External pins
+  *
+  * Pin  | GPIO | Name   | TMS9918A Pin
+  * -----+------+--------+-------------
+  *  19  |  14  |  CD0   |  24
+  *  20  |  15  |  CD1   |  23
+  *  21  |  16  |  CD2   |  22
+  *  22  |  17  |  CD3   |  21
+  *  24  |  18  |  CD4   |  20
+  *  25  |  19  |  CD5   |  19
+  *  26  |  20  |  CD6   |  18
+  *  27  |  21  |  CD7   |  17
+  *  29  |  22  |  /INT  |  16
+  *  30  |  RUN |  RST   |  34
+  *  31  |  26  |  /CSR  |  15
+  *  32  |  27  |  /CSW  |  14
+  *  34  |  28  |  MODE  |  13
+  */
+
+#define GPIO_CD0 14
+#define GPIO_CSR 26
+#define GPIO_CSW 27
+#define GPIO_MODE 28
+
+#define GPIO_CD_MASK (0xff << GPIO_CD0)
+#define GPIO_CSR_MASK (0x01 << GPIO_CSR)
+#define GPIO_CSW_MASK (0x01 << GPIO_CSW)
+#define GPIO_MODE_MASK (0x01 << GPIO_MODE)
+
+
+  /* todo should I make this uint32_t and shift the bits too?*/
+static uint32_t reversed[] =
+{
+  0x00, 0x80, 0x40, 0xC0, 0x20, 0xA0, 0x60, 0xE0, 0x10, 0x90, 0x50, 0xD0, 0x30, 0xB0, 0x70, 0xF0,
+  0x08, 0x88, 0x48, 0xC8, 0x28, 0xA8, 0x68, 0xE8, 0x18, 0x98, 0x58, 0xD8, 0x38, 0xB8, 0x78, 0xF8,
+  0x04, 0x84, 0x44, 0xC4, 0x24, 0xA4, 0x64, 0xE4, 0x14, 0x94, 0x54, 0xD4, 0x34, 0xB4, 0x74, 0xF4,
+  0x0C, 0x8C, 0x4C, 0xCC, 0x2C, 0xAC, 0x6C, 0xEC, 0x1C, 0x9C, 0x5C, 0xDC, 0x3C, 0xBC, 0x7C, 0xFC,
+  0x02, 0x82, 0x42, 0xC2, 0x22, 0xA2, 0x62, 0xE2, 0x12, 0x92, 0x52, 0xD2, 0x32, 0xB2, 0x72, 0xF2,
+  0x0A, 0x8A, 0x4A, 0xCA, 0x2A, 0xAA, 0x6A, 0xEA, 0x1A, 0x9A, 0x5A, 0xDA, 0x3A, 0xBA, 0x7A, 0xFA,
+  0x06, 0x86, 0x46, 0xC6, 0x26, 0xA6, 0x66, 0xE6, 0x16, 0x96, 0x56, 0xD6, 0x36, 0xB6, 0x76, 0xF6,
+  0x0E, 0x8E, 0x4E, 0xCE, 0x2E, 0xAE, 0x6E, 0xEE, 0x1E, 0x9E, 0x5E, 0xDE, 0x3E, 0xBE, 0x7E, 0xFE,
+  0x01, 0x81, 0x41, 0xC1, 0x21, 0xA1, 0x61, 0xE1, 0x11, 0x91, 0x51, 0xD1, 0x31, 0xB1, 0x71, 0xF1,
+  0x09, 0x89, 0x49, 0xC9, 0x29, 0xA9, 0x69, 0xE9, 0x19, 0x99, 0x59, 0xD9, 0x39, 0xB9, 0x79, 0xF9,
+  0x05, 0x85, 0x45, 0xC5, 0x25, 0xA5, 0x65, 0xE5, 0x15, 0x95, 0x55, 0xD5, 0x35, 0xB5, 0x75, 0xF5,
+  0x0D, 0x8D, 0x4D, 0xCD, 0x2D, 0xAD, 0x6D, 0xED, 0x1D, 0x9D, 0x5D, 0xDD, 0x3D, 0xBD, 0x7D, 0xFD,
+  0x03, 0x83, 0x43, 0xC3, 0x23, 0xA3, 0x63, 0xE3, 0x13, 0x93, 0x53, 0xD3, 0x33, 0xB3, 0x73, 0xF3,
+  0x0B, 0x8B, 0x4B, 0xCB, 0x2B, 0xAB, 0x6B, 0xEB, 0x1B, 0x9B, 0x5B, 0xDB, 0x3B, 0xBB, 0x7B, 0xFB,
+  0x07, 0x87, 0x47, 0xC7, 0x27, 0xA7, 0x67, 0xE7, 0x17, 0x97, 0x57, 0xD7, 0x37, 0xB7, 0x77, 0xF7,
+  0x0F, 0x8F, 0x4F, 0xCF, 0x2F, 0xAF, 0x6F, 0xEF, 0x1F, 0x9F, 0x5F, 0xDF, 0x3F, 0xBF, 0x7F, 0xFF
+};
+
+uint8_t regValue = 0;
+
+
+VrEmuTms9918* tms = NULL;
+
+
+void gpioCallback(uint gpio, uint32_t events)
+{
+  if (gpio == GPIO_CSR)
+  {
+    gpio_set_dir_out_masked(GPIO_CD_MASK);
+    uint32_t gpios = gpio_get_all();
+    if (gpios & GPIO_MODE_MASK)
+    {
+      gpio_put_masked(GPIO_CD_MASK, reversed[vrEmuTms9918ReadStatus(tms)] << GPIO_CD0);
+    }
+    else
+    {
+      gpio_put_masked(GPIO_CD_MASK, reversed[vrEmuTms9918ReadDataNoInc(tms)] << GPIO_CD0);
+      vrEmuTms9918ReadData(tms);
+    }
+  }
+  else if (gpio == GPIO_CSW)
+  {
+    gpio_set_dir_in_masked(GPIO_CD_MASK);
+    uint32_t gpios = gpio_get_all();
+    uint8_t value = reversed[(gpios >> GPIO_CD0) & 0xff];
+    if (gpios & GPIO_MODE_MASK)
+    {
+      vrEmuTms9918WriteAddr(tms, value);
+    }
+    else
+    {
+      vrEmuTms9918WriteData(tms, value);
+    }
+  }
+}
+
+
+
+uint16_t __aligned(4) tmsPal[16];
+uint8_t __aligned(4) tmsScanlineBuffer[TMS9918_PIXELS_X];
+
+uint16_t colorFromRgb(uint16_t r, uint16_t g, uint16_t b)
+{
+  return ((uint16_t)(r / 16.0f) & 0x0f) | (((uint16_t)(g / 16.0f) & 0x0f) << 4) | (((uint16_t)(b / 16.0f) & 0x0f) << 8);
+}
+
+static void tmsScanline(uint16_t y, VgaParams* params, uint16_t* pixels)
+{
+  const uint32_t vBorder = (params->vVirtualPixels - TMS9918_PIXELS_Y) / 2;
+  const uint32_t hBorder = (params->hVirtualPixels - TMS9918_PIXELS_X) / 2;
+
+  uint16_t bg = tmsPal[vrEmuTms9918RegValue(tms, TMS_REG_FG_BG_COLOR) & 0x0f];
+
+  if (y < vBorder || y >= (vBorder + TMS9918_PIXELS_Y))
+  {
+    for (int x = 0; x < params->hVirtualPixels; ++x)
+    {
+      pixels[x] = bg;
+    }
+    return;
+  }
+
+  y -= vBorder;
+
+  for (int x = 0; x < hBorder; ++x)
+  {
+    pixels[x] = bg;
+  }
+
+  vrEmuTms9918ScanLine(tms, y, tmsScanlineBuffer);
+
+  int tmsX = 0;
+  for (int x = hBorder; x < hBorder + TMS9918_PIXELS_X; ++x, ++tmsX)
+  {
+    pixels[x] = tmsPal[tmsScanlineBuffer[tmsX]];
+  }
+
+  for (int x = hBorder + TMS9918_PIXELS_X; x < params->hVirtualPixels; ++x)
+  {
+    pixels[x] = bg;
+  }
+}
+
+
+int main(void)
+{
+  set_sys_clock_khz(252000, false);
+
+  gpio_init_mask(GPIO_CD_MASK | GPIO_CSR_MASK | GPIO_CSW_MASK | GPIO_MODE_MASK);
+  gpio_set_dir_all_bits(0); // all inputs
+
+  // Set up TMS9918 external PINs first. This is a priority to capture early writes 
+  gpio_set_irq_enabled_with_callback(GPIO_CSW, GPIO_IRQ_EDGE_FALL, true, &gpioCallback);
+  gpio_set_irq_enabled(GPIO_CSR, GPIO_IRQ_EDGE_FALL, true);
+
+  tms = vrEmuTms9918New();
+
+  for (int c = 0; c < 16; ++c)
+  {
+    uint32_t rgba8 = vrEmuTms9918Palette[c];
+    tmsPal[c] = colorFromRgb((rgba8 & 0xff000000) >> 24, (rgba8 & 0xff0000) >> 16, (rgba8 & 0xff00) >> 8);
+  }
+
+  // Then set up VGA output
+  VgaInitParams params = { 0 };
+  params.params = vgaGetParams(VGA_640_480_60HZ, 2);
+  params.scanlineFn = tmsScanline;
+
+
+  vgaInit(params);
+
+  while (1)
+  {
+    tight_loop_contents();
+  }
+
+  return 0;
+}

src/pio-utils/CMakeLists.txt

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+cmake_minimum_required(VERSION 3.12)
+
+set(LIBRARY pico9918-pio-utils)
+
+project (${LIBRARY} C)
+
+set(CMAKE_C_STANDARD 11)
+
+add_library(${LIBRARY} STATIC pio_utils.c)
+
+target_include_directories (${LIBRARY} INTERFACE ${CMAKE_CURRENT_SOURCE_DIR})
+
+target_link_libraries(${LIBRARY} PUBLIC hardware_pio)