From ae470397d7321cff020a4fe681657877799e6b41 Mon Sep 17 00:00:00 2001
From: Virgil Dupras <hsoft@hardcoded.net>
Date: Fri, 17 Apr 2020 15:11:32 -0400
Subject: [PATCH 1/3] emul/hw/rc2014: add sdc emulator (wip)

so far, it goes through initialization with the rc2014/sdcard recipe.
---
 emul/hw/rc2014/Makefile  |   2 +-
 emul/hw/rc2014/classic.c |  30 +++++++++++++
 emul/hw/rc2014/sdc.c     | 114 +++++++++++++++++++++++++++++++++++++++++++++++
 emul/hw/rc2014/sdc.h     |  28 ++++++++++++
 4 files changed, 173 insertions(+), 1 deletion(-)
 create mode 100644 emul/hw/rc2014/sdc.c
 create mode 100644 emul/hw/rc2014/sdc.h

diff --git a/emul/hw/rc2014/Makefile b/emul/hw/rc2014/Makefile
index 3ba5a7b..1ed63a4 100644
--- a/emul/hw/rc2014/Makefile
+++ b/emul/hw/rc2014/Makefile
@@ -1,5 +1,5 @@
 EXTOBJS = ../../emul.o ../../libz80/libz80.o
-OBJS = acia.o classic.o 
+OBJS = acia.o sdc.o classic.o 
 TARGET = classic
 
 .PHONY: all
diff --git a/emul/hw/rc2014/classic.c b/emul/hw/rc2014/classic.c
index 1f58e49..1791dfd 100644
--- a/emul/hw/rc2014/classic.c
+++ b/emul/hw/rc2014/classic.c
@@ -13,13 +13,18 @@
 #include <termios.h>
 #include "../../emul.h"
 #include "acia.h"
+#include "sdc.h"
 
 #define RAMSTART 0x8000
 #define ACIA_CTL_PORT 0x80
 #define ACIA_DATA_PORT 0x81
+#define SDC_CSHIGH 0x06
+#define SDC_CSLOW 0x05
+#define SDC_SPI 0x04
 #define MAX_ROMSIZE 0x2000
 
 static ACIA acia;
+static SDC sdc;
 
 static uint8_t iord_acia_ctl()
 {
@@ -41,6 +46,26 @@ static void iowr_acia_data(uint8_t val)
     acia_data_wr(&acia, val);
 }
 
+static uint8_t iord_sdc_spi()
+{
+    return sdc_spi_rd(&sdc);
+}
+
+static void iowr_sdc_spi(uint8_t val)
+{
+    sdc_spi_wr(&sdc, val);
+}
+
+static void iowr_sdc_cshigh(uint8_t val)
+{
+    sdc_cshigh(&sdc);
+}
+
+static void iowr_sdc_cslow(uint8_t val)
+{
+    sdc_cslow(&sdc);
+}
+
 int main(int argc, char *argv[])
 {
     if (argc != 2) {
@@ -81,10 +106,15 @@ int main(int argc, char *argv[])
     }
 
     acia_init(&acia);
+    sdc_init(&sdc);
     m->iord[ACIA_CTL_PORT] = iord_acia_ctl;
     m->iord[ACIA_DATA_PORT] = iord_acia_data;
     m->iowr[ACIA_CTL_PORT] = iowr_acia_ctl;
     m->iowr[ACIA_DATA_PORT] = iowr_acia_data;
+    m->iord[SDC_SPI] = iord_sdc_spi;
+    m->iowr[SDC_SPI] = iowr_sdc_spi;
+    m->iowr[SDC_CSHIGH] = iowr_sdc_cshigh;
+    m->iowr[SDC_CSLOW] = iowr_sdc_cslow;
 
     char tosend = 0;
     while (emul_step()) {
diff --git a/emul/hw/rc2014/sdc.c b/emul/hw/rc2014/sdc.c
new file mode 100644
index 0000000..f863038
--- /dev/null
+++ b/emul/hw/rc2014/sdc.c
@@ -0,0 +1,114 @@
+#include <stdio.h>
+#include "sdc.h"
+
+void sdc_init(SDC *sdc)
+{
+    sdc->selected = false;
+    sdc->initstat = 0;
+    sdc->recvidx = 0;
+    sdc->sendidx = -1;
+    sdc->resp = 0xff;
+}
+
+void sdc_cslow(SDC *sdc)
+{
+    sdc->selected = true;
+}
+
+void sdc_cshigh(SDC *sdc)
+{
+    sdc->selected = false;
+}
+
+void sdc_spi_wr(SDC *sdc, uint8_t val)
+{
+    if (!sdc->selected) {
+        return;
+    }
+    sdc->resp = 0xff;
+    if (sdc->initstat < 8) {
+        // not woken yet.
+        sdc->initstat++;
+        return;
+    }
+    if (sdc->sendidx >= 0) {
+        sdc->resp = sdc->sendbuf[sdc->sendidx++];
+        if (sdc->sendidx == 5) {
+            sdc->sendidx = -1;
+        }
+        return;
+    }
+    if ((sdc->recvidx == 0) && ((val > 0x7f) || (val < 0x40))) {
+        // not a command
+        return;
+    }
+    sdc->recvbuf[sdc->recvidx++] = val;
+    if (sdc->recvidx < 6) {
+        // incomplete command
+        return;
+    }
+    // Command complete
+    val &= 0x3f;
+    sdc->recvidx = 0;
+    uint8_t *b = sdc->recvbuf;
+    fprintf(stderr, "cmd %02x %02x %02x %02x %02x\n", b[0], b[1], b[2], b[3], b[4]);
+    uint8_t cmd = b[0] & 0x3f;
+    if (sdc->initstat == 8) {
+        // At this stage, we're expecting CMD0
+        if (cmd == 0) {
+            sdc->initstat++;
+            sdc->sendbuf[4] = 0x01;
+            sdc->sendidx = 4;
+        }
+        return;
+    }
+    if (sdc->initstat == 9) {
+        // At this stage, we're expecting CMD8 with 0x1aa arg2
+        if ((cmd == 8) && (b[3] == 0x01) && (b[4] == 0xaa)) {
+            sdc->initstat++;
+            sdc->sendbuf[0] = 0x01;
+            sdc->sendbuf[1] = 0;
+            sdc->sendbuf[2] = 0;
+            sdc->sendbuf[3] = 0x01;
+            sdc->sendbuf[4] = 0xaa;
+            sdc->sendidx = 0;
+        } else {
+            sdc-> initstat = 8;
+        }
+        return;
+    }
+    if (sdc->initstat == 10) {
+        // At this stage, we're expecting CMD55
+        if (cmd == 55) {
+            sdc->initstat++;
+            sdc->sendbuf[4] = 0x01;
+            sdc->sendidx = 4;
+        } else {
+            sdc->initstat = 8;
+        }
+        return;
+    }
+    if (sdc->initstat == 11) {
+        // At this stage, we're expecting CMD41
+        if ((cmd == 41) && (b[1] == 0x40) && (b[2] == 0x00)) {
+            sdc->initstat++;
+            sdc->sendbuf[4] = 0x00;
+            sdc->sendidx = 4;
+        } else {
+            sdc->initstat = 8;
+        }
+        return;
+    }
+    // We have a fully initialized card.
+    // Simulate success for any unknown command.
+    sdc->sendbuf[4] = 0x00;
+    sdc->sendidx = 4;
+}
+
+uint8_t sdc_spi_rd(SDC *sdc)
+{
+    if (!sdc->selected) {
+        return 0xff;
+    }
+    return sdc->resp;
+}
diff --git a/emul/hw/rc2014/sdc.h b/emul/hw/rc2014/sdc.h
new file mode 100644
index 0000000..22748cd
--- /dev/null
+++ b/emul/hw/rc2014/sdc.h
@@ -0,0 +1,28 @@
+#include <stdint.h>
+#include <stdbool.h>
+
+typedef struct {
+    bool selected;
+    // Initialization status. 0 == not woken 8 == woken 9 == CMD0 received
+    // 10 == CMD8 received, 11 == CMD55 received, 12 == CMD41 received (fully
+    // initialized).
+    unsigned int initstat;
+    // We receive commands into this buffer.
+    uint8_t recvbuf[6];
+    // Where the next SPI byte should be stored in recvbuf.
+    unsigned int recvidx;
+    // Buffer to the arguments for a response
+    uint8_t sendbuf[5];
+    // Index of the next byte from sendbuf we should return. If -1, buffer is
+    // empty.
+    int sendidx;
+    // One byte response. When all other response buffers are empty, return
+    // this.
+    uint8_t resp;
+} SDC;
+
+void sdc_init(SDC *sdc);
+void sdc_cslow(SDC *sdc);
+void sdc_cshigh(SDC *sdc);
+void sdc_spi_wr(SDC *sdc, uint8_t val);
+uint8_t sdc_spi_rd(SDC *sdc);

From 7544b3834b1b6c195d974185ad59dd2d17dd8073 Mon Sep 17 00:00:00 2001
From: Virgil Dupras <hsoft@hardcoded.net>
Date: Fri, 17 Apr 2020 19:10:22 -0400
Subject: [PATCH 2/3] emul/hw/rc2014: implement blkread in sdc

I now get to "fls" in recipes/rc2014/sdcard!
---
 emul/hw/rc2014/classic.c | 11 +++++++++--
 emul/hw/rc2014/sdc.c     | 45 ++++++++++++++++++++++++++++++++++++++++++---
 emul/hw/rc2014/sdc.h     |  6 ++++++
 3 files changed, 57 insertions(+), 5 deletions(-)

diff --git a/emul/hw/rc2014/classic.c b/emul/hw/rc2014/classic.c
index 1791dfd..f04003d 100644
--- a/emul/hw/rc2014/classic.c
+++ b/emul/hw/rc2014/classic.c
@@ -68,8 +68,8 @@ static void iowr_sdc_cslow(uint8_t val)
 
 int main(int argc, char *argv[])
 {
-    if (argc != 2) {
-        fprintf(stderr, "Usage: ./classic /path/to/rom\n");
+    if (argc < 2) {
+        fprintf(stderr, "Usage: ./classic /path/to/rom [sdcard.img]\n");
         return 1;
     }
     FILE *fp = fopen(argv[1], "r");
@@ -107,6 +107,10 @@ int main(int argc, char *argv[])
 
     acia_init(&acia);
     sdc_init(&sdc);
+    if (argc == 3) {
+        fprintf(stderr, "Setting up SD card image\n");
+        sdc.fp = fopen(argv[2], "r+");
+    }
     m->iord[ACIA_CTL_PORT] = iord_acia_ctl;
     m->iord[ACIA_DATA_PORT] = iord_acia_data;
     m->iowr[ACIA_CTL_PORT] = iowr_acia_ctl;
@@ -152,5 +156,8 @@ int main(int argc, char *argv[])
         tcsetattr(0, TCSADRAIN, &saved_term);
         emul_printdebug();
     }
+    if (sdc.fp) {
+        fclose(sdc.fp);
+    }
     return 0;
 }
diff --git a/emul/hw/rc2014/sdc.c b/emul/hw/rc2014/sdc.c
index f863038..9560698 100644
--- a/emul/hw/rc2014/sdc.c
+++ b/emul/hw/rc2014/sdc.c
@@ -1,6 +1,16 @@
 #include <stdio.h>
 #include "sdc.h"
 
+// Add data to crc with polynomial 0x1021
+// https://stackoverflow.com/a/23726131
+static uint16_t crc16(uint16_t crc, uint8_t data)
+{
+    uint8_t x = crc >> 8 ^ data;
+    x ^= x>>4;
+    crc = (crc << 8) ^ ((uint16_t)(x << 12)) ^ ((uint16_t)(x <<5)) ^ ((uint16_t)x);
+    return crc;
+}
+
 void sdc_init(SDC *sdc)
 {
     sdc->selected = false;
@@ -8,6 +18,8 @@ void sdc_init(SDC *sdc)
     sdc->recvidx = 0;
     sdc->sendidx = -1;
     sdc->resp = 0xff;
+    sdc->fp = NULL;
+    sdc->cmd17bytes = -1;
 }
 
 void sdc_cslow(SDC *sdc)
@@ -38,6 +50,20 @@ void sdc_spi_wr(SDC *sdc, uint8_t val)
         }
         return;
     }
+    if (sdc->cmd17bytes >= 0) {
+        if (sdc->fp) {
+            sdc->resp = getc(sdc->fp);
+        }
+        sdc->crc16 = crc16(sdc->crc16, sdc->resp);
+        sdc->cmd17bytes++;
+        if (sdc->cmd17bytes == 512) {
+            sdc->sendbuf[3] = sdc->crc16 >> 8;
+            sdc->sendbuf[4] = sdc->crc16 & 0xff;
+            sdc->sendidx = 3;
+            sdc->cmd17bytes = -1;
+        }
+        return;
+    }
     if ((sdc->recvidx == 0) && ((val > 0x7f) || (val < 0x40))) {
         // not a command
         return;
@@ -51,8 +77,9 @@ void sdc_spi_wr(SDC *sdc, uint8_t val)
     val &= 0x3f;
     sdc->recvidx = 0;
     uint8_t *b = sdc->recvbuf;
-    fprintf(stderr, "cmd %02x %02x %02x %02x %02x\n", b[0], b[1], b[2], b[3], b[4]);
     uint8_t cmd = b[0] & 0x3f;
+    uint16_t arg1 = (b[1] << 8) | b[2];
+    uint16_t arg2 = (b[3] << 8) | b[4];
     if (sdc->initstat == 8) {
         // At this stage, we're expecting CMD0
         if (cmd == 0) {
@@ -64,7 +91,7 @@ void sdc_spi_wr(SDC *sdc, uint8_t val)
     }
     if (sdc->initstat == 9) {
         // At this stage, we're expecting CMD8 with 0x1aa arg2
-        if ((cmd == 8) && (b[3] == 0x01) && (b[4] == 0xaa)) {
+        if ((cmd == 8) && (arg2 == 0x01aa)) {
             sdc->initstat++;
             sdc->sendbuf[0] = 0x01;
             sdc->sendbuf[1] = 0;
@@ -90,7 +117,7 @@ void sdc_spi_wr(SDC *sdc, uint8_t val)
     }
     if (sdc->initstat == 11) {
         // At this stage, we're expecting CMD41
-        if ((cmd == 41) && (b[1] == 0x40) && (b[2] == 0x00)) {
+        if ((cmd == 41) && (arg1 == 0x4000)) {
             sdc->initstat++;
             sdc->sendbuf[4] = 0x00;
             sdc->sendidx = 4;
@@ -100,6 +127,18 @@ void sdc_spi_wr(SDC *sdc, uint8_t val)
         return;
     }
     // We have a fully initialized card.
+    if (cmd == 17) {
+        if (sdc->fp) {
+            fseek(sdc->fp, arg2*512, SEEK_SET);
+        }
+        sdc->sendbuf[3] = 0x00;
+        // data token
+        sdc->sendbuf[4] = 0xfe;
+        sdc->sendidx = 3;
+        sdc->cmd17bytes = 0;
+        sdc->crc16 = 0;
+        return;
+    }
     // Simulate success for any unknown command.
     sdc->sendbuf[4] = 0x00;
     sdc->sendidx = 4;
diff --git a/emul/hw/rc2014/sdc.h b/emul/hw/rc2014/sdc.h
index 22748cd..0d5aa19 100644
--- a/emul/hw/rc2014/sdc.h
+++ b/emul/hw/rc2014/sdc.h
@@ -19,6 +19,12 @@ typedef struct {
     // One byte response. When all other response buffers are empty, return
     // this.
     uint8_t resp;
+    // File used for contents read/write
+    FILE *fp;
+    // number of bytes read into the current CMD17. -1 means no CMD17 active.
+    int cmd17bytes;
+    // running crc16 during read and write operations.
+    uint16_t crc16;
 } SDC;
 
 void sdc_init(SDC *sdc);

From 9c41744e46eec7e48635c78609244ddc0ce5e706 Mon Sep 17 00:00:00 2001
From: Virgil Dupras <hsoft@hardcoded.net>
Date: Fri, 17 Apr 2020 20:19:55 -0400
Subject: [PATCH 3/3] emul/hw/rc2014: implement blk write in sdc

All of that should help me implement sdc support much faster in
Forth.
---
 emul/hw/rc2014/sdc.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 emul/hw/rc2014/sdc.h |  3 +++
 2 files changed, 56 insertions(+)

diff --git a/emul/hw/rc2014/sdc.c b/emul/hw/rc2014/sdc.c
index 9560698..b684048 100644
--- a/emul/hw/rc2014/sdc.c
+++ b/emul/hw/rc2014/sdc.c
@@ -20,6 +20,7 @@ void sdc_init(SDC *sdc)
     sdc->resp = 0xff;
     sdc->fp = NULL;
     sdc->cmd17bytes = -1;
+    sdc->cmd24bytes = -2;
 }
 
 void sdc_cslow(SDC *sdc)
@@ -64,6 +65,47 @@ void sdc_spi_wr(SDC *sdc, uint8_t val)
         }
         return;
     }
+    if (sdc->cmd24bytes == -1) {
+        if (val == 0xff) {
+            // it's ok to receive idle bytes before the data token.
+            return;
+        }
+        if (val == 0xfe) {
+            // data token, good
+            sdc->cmd24bytes = 0;
+        } else {
+            // something is wrong, cancel cmd24
+            sdc->cmd24bytes = -2;
+        }
+        return;
+    }
+    if (sdc->cmd24bytes >= 0) {
+        if (sdc->cmd24bytes < 512) {
+            if (sdc->fp) {
+                putc(val, sdc->fp);
+            }
+            sdc->crc16 = crc16(sdc->crc16, val);
+        } else if (sdc->cmd24bytes == 512) {
+            // CRC MSB
+            if (val == (sdc->crc16>>8)) {
+                fprintf(stderr, "Good CRC16 MSB\n");
+            } else {
+                fprintf(stderr, "Bad CRC16 MSB\n");
+            }
+        } else {
+            if (val == (sdc->crc16&0xff)) {
+                fprintf(stderr, "Good CRC16 LSB\n");
+            } else {
+                fprintf(stderr, "Bad CRC16 LSB\n");
+            }
+            // valid response for CMD24
+            sdc->sendbuf[4] = 0x05;
+            sdc->sendidx = 4;
+            sdc->cmd24bytes = -3;
+        }
+        sdc->cmd24bytes++;
+        return;
+    }
     if ((sdc->recvidx == 0) && ((val > 0x7f) || (val < 0x40))) {
         // not a command
         return;
@@ -139,6 +181,17 @@ void sdc_spi_wr(SDC *sdc, uint8_t val)
         sdc->crc16 = 0;
         return;
     }
+    if (cmd == 24) {
+        fprintf(stderr, "cmd24\n");
+        if (sdc->fp) {
+            fseek(sdc->fp, arg2*512, SEEK_SET);
+        }
+        sdc->sendbuf[4] = 0x00;
+        sdc->sendidx = 4;
+        sdc->cmd24bytes = -1;
+        sdc->crc16 = 0;
+        return;
+    }
     // Simulate success for any unknown command.
     sdc->sendbuf[4] = 0x00;
     sdc->sendidx = 4;
diff --git a/emul/hw/rc2014/sdc.h b/emul/hw/rc2014/sdc.h
index 0d5aa19..6a84ecb 100644
--- a/emul/hw/rc2014/sdc.h
+++ b/emul/hw/rc2014/sdc.h
@@ -23,6 +23,9 @@ typedef struct {
     FILE *fp;
     // number of bytes read into the current CMD17. -1 means no CMD17 active.
     int cmd17bytes;
+    // number of bytes received for the current CMD24. -2 means no CMD24 active.
+    // -1 means we're still waiting for the data token.
+    int cmd24bytes;
     // running crc16 during read and write operations.
     uint16_t crc16;
 } SDC;