SD cardgit status FAT32git status Beautiful!

15 files changed, 706 insertions, 31 deletions

diff --git a/Makefile b/Makefile
index d672a52..595694a 100644
--- a/Makefile
+++ b/Makefile
@@ -46,7 +46,7 @@ INITRD = initrd.img
 
 all: $(OUT)
 
-$(OUT): $(OFILES) initrd/init libinterp.a
+$(OUT): $(OFILES) initrd/* libinterp.a
 	@echo "  INITRD " $(INITRD)
 	@rm -f $(INITRD)
 	@$(AR) $(INITRD) initrd/*
diff --git a/include/display.h b/include/display.h
index b8afe38..2d74fce 100644
--- a/include/display.h
+++ b/include/display.h
@@ -92,4 +92,7 @@ void dsp_set_addr(uint16_t x1, uint16_t y1, uint16_t x2, uint16_t y2);
  */
 void dsp_set_addr_read(uint16_t x1, uint16_t y1, uint16_t x2, uint16_t y2);
 
+void dsp_sleep(void);
+void dsp_wakeup(void);
+
 #endif // DISPLAY_H_
diff --git a/include/fat32.h b/include/fat32.h
new file mode 100644
index 0000000..39d22f6
--- /dev/null
+++ b/include/fat32.h
@@ -0,0 +1,31 @@
+#ifndef FAT32_H_
+#define FAT32_H_
+
+#include <stdint.h>
+
+typedef struct {
+	uint32_t size;	
+	uint32_t start;
+} file_t;
+
+/**
+ * Finds a FAT partition on the SD card.
+ * @return non-zero if partition found
+ */
+int fat_find(void);
+
+/**
+ * Searches for the given file, returning necessary information to use it.
+ * @param name the file's name
+ * @return a file data structure, null if not found
+ */
+file_t *fat_findfile(const char *name);
+
+/**
+ * 
+ */
+char *fat_readfile(file_t *file);
+
+char *fat_getname(uint32_t index);
+
+#endif // FAT32_H_
diff --git a/include/sdcard.h b/include/sdcard.h
new file mode 100644
index 0000000..8cdef58
--- /dev/null
+++ b/include/sdcard.h
@@ -0,0 +1,42 @@
+/**
+ * @file sdcard.c
+ * Provides a basic library for accessing an SD card
+ *
+ * Copyright (C) 2018 Clyne Sullivan
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef SDCARD_H_
+#define SDCARD_H_
+
+#include <stdint.h>
+
+/**
+ * Attempts to initialize the SD card.
+ * Warning: Little to no error checking is done/handled properly.
+ */
+void sd_init(void);
+
+/**
+ * Reads in data from the SD card.
+ * LBAs are 512 bytes long.
+ * @param buf the pre-allocated buffer to store data in
+ * @param lba the lba to read from
+ * @param count the number of bytes to read
+ * @return the buffer
+ */
+uint8_t *sd_read(uint8_t *buf, uint32_t lba, uint32_t count);
+
+#endif // SDCARD_H_
diff --git a/initrd/graph b/initrd/graph
index 8f9916a..949fd52 100644
--- a/initrd/graph
+++ b/initrd/graph
@@ -41,24 +41,24 @@ func(makegrid) {
 #
 
 makegrid()
-clearcmd = "clear"
+clearcmd = ""
 while (1) {
 	rect(0, 0, 480, 40, 0)
 	print("f(x) = ")
-	Fx = gets()
+	fx = gets()
 
-	if (Fx == clearcmd) {
+	if (fx == clearcmd) {
 		makegrid()
 	} else {
 		# do function
-		x = xmin
-		while (x < xmax) {
-			y = solve(Fx)
+		X = xmin
+		while (X < xmax) {
+			y = solve(fx)
 			y = 0 - y
 			if ((y >= ymin) & (y <= ymax)) {
-				pixel(cx + x * xinc, cy + y * yinc, 511)
+				pixel(cx + X * xinc, cy + y * yinc, 511)
 			}
-			x = x + 1 / xinc
+			X = X + 1 / xinc
 		}
 	}
 
diff --git a/initrd/table b/initrd/table
new file mode 100644
index 0000000..62961e3
--- /dev/null
+++ b/initrd/table
@@ -0,0 +1,85 @@
+ppos(0, 0)
+array(table, 1)
+
+index = 0
+while (1) {
+	c = getkey()
+	# down
+	if (c == 25) {
+		rpos(0, 1)
+		index = index + 1
+	}
+	# up
+	if (c == 24) {
+		rpos(0, -1)
+		if (index > 0) {
+			index = index - 1
+		}
+	}
+	# right - insert
+	if (c == 26) {
+		print("          ")
+		rpos(-10, 0)
+		print("> ")
+		table.index = getf()
+		ppos(0, index)
+		print(index)
+		print(": ")
+		print(table.index)
+		print("         ")
+		index = index + 1
+		ppos(0, index)
+	}
+	# plus - sum
+	if (c == 43) {
+		s = size(table)
+		j = 0
+		sum = 0
+		while (j < s) {
+			sum = sum + table.j
+			j = j + 1
+		}
+		ppos(0, 17)
+		print("                    ")
+		ppos(0, 17)
+		print("sum: ")
+		print(sum)
+		ppos(0, 0)
+		index = 0
+	}
+	# * - product
+	if (c == 42) {
+		s = size(table)
+		j = 0
+		product = 1
+		while (j < s) {
+			product = product * table.j
+			j = j + 1
+		}
+		ppos(0, 17)
+		print("                    ")
+		ppos(0, 17)
+		print("product: ")
+		print(product)
+		ppos(0, 0)
+		index = 0
+	}
+	# / - average
+	if (c == 47) {
+		s = size(table)
+		j = 0
+		sum = 0
+		while (j < s) {
+			sum = sum + table.j
+			j = j + 1
+		}
+		average = sum / size(table)
+		ppos(0, 17)
+		print("                    ")
+		ppos(0, 17)
+		print("average: ")
+		print(average)
+		ppos(0, 0)
+		index = 0
+	}
+}
diff --git a/libinterp.a b/libinterp.a
index 5b5da09..c5a2337 100644
--- a/libinterp.a
+++ b/libinterp.a
diff --git a/src/display.c b/src/display.c
index e961299..376ba43 100644
--- a/src/display.c
+++ b/src/display.c
@@ -206,7 +206,13 @@ void dsp_init(void)
 	dsp_write_cmd(0x11);
 	delay(150);
 	dsp_write_cmd(0x29); // set display on
-	delay(500);
+	delay(150);
+
+	dsp_write_cmd(0x53);
+	dsp_write_data(0x2C);
+	//dsp_write_cmd(0x51);
+	//dsp_write_data(128);
+
 	/*dsp_write_cmd(0x33); // set scroll area
 	dsp_write_data(0x00);
 	dsp_write_data(0x00);
@@ -219,3 +225,32 @@ void dsp_init(void)
 	dsp_write_data(0x00);*/
 }
 
+void dsp_backlight(uint8_t value)
+{
+	dsp_write_cmd(0x51);
+	dsp_write_data(value);
+}
+
+void dsp_sleep(void)
+{
+	// backlight
+	dsp_backlight(0x00);
+	// display off
+	dsp_write_cmd(0x28);
+	// sleep mode
+	dsp_write_cmd(0x10);
+	delay(5);
+}
+
+void dsp_wakeup(void)
+{
+	// unsleep
+	dsp_write_cmd(0x11);
+	//delay(5);
+	for (uint32_t i = 0; i < 20000; i++)
+		asm("");
+	// display on
+	dsp_write_cmd(0x29);
+	dsp_backlight(0xFF);
+}
+
diff --git a/src/fat32.c b/src/fat32.c
new file mode 100644
index 0000000..1154998
--- /dev/null
+++ b/src/fat32.c
@@ -0,0 +1,145 @@
+/**
+ * Implementation of a driver to read a FAT32 filesystem.
+ */
+
+#include <ctype.h>
+#include <fat32.h>
+#include <heap.h>
+#include <sdcard.h>
+#include <string.h>
+
+static uint32_t partition_lba = 0;
+
+static uint8_t SectorsPerCluster;
+static uint32_t RootDirCluster;
+static uint32_t ClustersLBA;
+static uint32_t FATStartLBA;
+
+int fat_find(void)
+{
+	uint8_t *block = malloc(512);
+
+	// find FAT partition
+	sd_read(block, 0, 512);
+	for (unsigned int i = 450; i < 450 + 64; i += 16) {
+		if (block[i] == 0x0B || block[i] == 0x0C) {
+			partition_lba = *((uint32_t *)(block + i + 4));
+			break;
+		}
+	}
+
+	if (partition_lba == 0)
+		return 0;
+
+	// read FAT volume id
+	sd_read(block, partition_lba, 512);
+	SectorsPerCluster = block[0x0D];
+	uint16_t ReservedSectors = *((uint16_t *)(block + 0x0E));
+	uint32_t SectorsPerFAT = *((uint32_t *)(block + 0x24));
+	RootDirCluster = *((uint32_t *)(block + 0x2C));
+
+	FATStartLBA = partition_lba + ReservedSectors;
+	ClustersLBA = FATStartLBA + 2 * SectorsPerFAT;
+
+	free(block);
+	return 1;
+}
+
+uint32_t fat_cluster2lba(uint32_t cluster)
+{
+	return ClustersLBA + (cluster - 2) * SectorsPerCluster;
+}
+
+int fat_namecmp(const char *fatname, const char *name)
+{
+	for (unsigned int i = 0; i < 8; i++) {
+		if (name[i] == '.' || name[i] == '\0')
+			break;
+
+		if (toupper(fatname[i]) != toupper(name[i]))
+			return 0;
+	}
+
+	return 1;
+}
+
+file_t *fat_findfile(const char *name)
+{
+	uint8_t *block = malloc(512 * SectorsPerCluster);
+	sd_read(block, fat_cluster2lba(RootDirCluster), 512 * SectorsPerCluster);
+
+	for (unsigned int i = 0; block[i * 32] != 0; i++) {
+		if (block[i * 32] == 0xE5 || (block[i * 32 + 11] & 0x0F) == 0x0F)
+			continue;
+
+		if (fat_namecmp((char *)(block + i * 32), name)) {
+			uint32_t size = *((uint32_t *)(block + i * 32 + 28));
+			uint32_t start = *((uint16_t *)(block + i * 32 + 20))
+				<< 16 | *((uint16_t *)(block + i * 32 + 26));
+			file_t *file = malloc(sizeof(file_t));
+			file->size = size;
+			file->start = start;
+			free(block);
+			return file;
+		}
+	}
+
+	free(block);
+	return 0;
+}
+
+char *fat_getname(uint32_t index)
+{
+	uint8_t *block = malloc(512 * SectorsPerCluster);
+	sd_read(block, fat_cluster2lba(RootDirCluster), 512 * SectorsPerCluster);
+
+	uint32_t idx = 0;
+	for (unsigned int i = 0; block[i * 32] != 0; i++) {
+		if (block[i * 32] == 0xE5 || (block[i * 32 + 11] & 0x0F) == 0x0F)
+			continue;
+
+		if (idx == index) {
+			char *name = strncpy(malloc(11), (char *)(block + i * 32), 11);
+			free(block);
+			return name;
+		}
+		idx++;
+	}
+
+	free(block);
+	return 0;
+}
+
+char *fat_readfile(file_t *file)
+{
+	if (file == 0)
+		return 0;
+
+	uint8_t *block = malloc(512);
+
+	uint32_t start = file->start;
+	uint8_t *buffer = malloc(file->size + 1);
+	uint32_t offset = 0;
+	buffer[file->size] = '\0';
+	while (start != 0) {
+		// find in FAT
+		sd_read(block, FATStartLBA + (start / 128), 512);
+		uint32_t next = ((uint32_t *)block)[start % 128];
+
+		// read start cluster
+		uint32_t size = 512 * SectorsPerCluster;
+		if (file->size - offset < size)
+			size = file->size - offset;
+		sd_read(buffer, fat_cluster2lba(start), size);
+		offset += size;
+
+		if ((next & 0x0FFFFFFF) == 0x0FFFFFFF)
+			start = 0;
+		else
+			start = next;
+
+	}
+
+	free(block);
+	return (char *)buffer;
+}
diff --git a/src/gpio.c b/src/gpio.c
index db67465..151779d 100644
--- a/src/gpio.c
+++ b/src/gpio.c
@@ -23,7 +23,7 @@
 void gpio_init(void)
 {
 	// enable clocks
-	RCC->AHB2ENR |= 0xFF;
+	RCC->AHB2ENR |= 0x0F;
 }
 
 void gpio_pupd(GPIO_TypeDef *port, uint32_t pin, uint32_t pupd)
diff --git a/src/keypad.c b/src/keypad.c
index b00cf41..cb569e1 100644
--- a/src/keypad.c
+++ b/src/keypad.c
@@ -35,6 +35,8 @@
 #define COL_3 GPIO_PORT(A, 12)
 #define COL_4 GPIO_PORT(C, 5)
 
+#define BTN_SLEEP GPIO_PORT(C, 11)
+
 #define ROWS 6
 #define COLS 5
 
@@ -59,7 +61,7 @@ static const port_t keypad_cols[COLS] = {
 
 static const char keypad_map[ROWS * COLS * 4] = {
 	"\x7F\0\0\0" "\xFF\0\0\0" "\xFF\x02\0\0" "\x19\0\0\0" "\x18\0\0\0"
-	"x\0\0\0"    "\0\0\0\0"   "\0\0\0\0" "\x1B\0\0\0" "\x1A\0\0\0"
+	"sin\0"      "cos\0"      "tan\0"    "\x1B\0\0\0" "\x1A\0\0\0"
 	"7\0\0\0"    "8\0\0\0"    "9\0\0\0"  "(\0\0\0"    ")\0\0\0"
 	"4\0\0\0"    "5\0\0\0"    "6\0\0\0"  "/\0\0\0"    "*\0\0\0"
 	"1\0\0\0"    "2\0\0\0"    "3\0\0\0"  "-\0\0\0"    "+\0\0\0"
@@ -67,12 +69,12 @@ static const char keypad_map[ROWS * COLS * 4] = {
 };
 
 static const char keypad_map_2nd[ROWS * COLS * 4] = {
-	"a\0\0\0" "b\0\0\0"  "c\0\0\0"  "d\0\0\0"  "e\0\0\0"
-	"f\0\0\0" "g\0\0\0"  "h\0\0\0"  "i\0\0\0"  "j\0\0\0"
-	"k\0\0\0" "l\0\0\0"  "m\0\0\0"  "n\0\0\0"  "o\0\0\0"
-	"p\0\0\0" "q\0\0\0"  "r\0\0\0"  "s\0\0\0"  "t\0\0\0"
-	"u\0\0\0" "v\0\0\0"  "w\0\0\0"  "x\0\0\0"  "y\0\0\0"
-	"z\0\0\0" "\0\0\0\0" "\0\0\0\0" "\0\0\0\0" "\xFF\x01\0\0"
+	"\x7F\0\0\0" "pi\0\0"  "X\0\0\0" "Y\0\0\0"  "Z\0\0\0"
+	"A\0\0\0"    "B\0\0\0" "C\0\0\0" "D\0\0\0"  "E\0\0\0"
+	"F\0\0\0"    "G\0\0\0" "H\0\0\0" "I\0\0\0"  "J\0\0\0"
+	"K\0\0\0"    "L\0\0\0" "M\0\0\0" "N\0\0\0"  "O\0\0\0"
+	"P\0\0\0"    "Q\0\0\0" "R\0\0\0" "S\0\0\0"  "T\0\0\0"
+	"U\0\0\0"    "V\0\0\0" "W\0\0\0" "\b\0\0\0" "\xFF\x01\0\0"
 };
 
 #define KEY(r, c, i) map[r * COLS * 4 + c * 4 + i]
@@ -142,6 +144,19 @@ void keypad_init(void)
 		gpio_speed(p, pin, VERYHIGH);
 		gpio_dout(p, pin, 0);
 	}
+
+	gpio_mode(BTN_SLEEP, OUTPUT);
+	gpio_dout(BTN_SLEEP, 0);
+	gpio_mode(BTN_SLEEP, INPUT);
+	gpio_pupd(BTN_SLEEP, PULLDOWN);
+
+	//SYSCFG->EXTICR[2] |= 0x200; // C10
+	EXTI->RTSR1 |= (1 << 11);
+	EXTI->EMR1 |= (1 << 11); // Allow *10
+	EXTI->IMR1 |= (1 << 11);
+
+	// enable IRQ in NVIC
+	((uint32_t *)0xE000E100)[1] |= (1 << 8);
 }
 
 void keypad_start(void)
@@ -160,3 +175,24 @@ int keypad_get(void)
 	keypad_buffer_pos--;
 	return key;
 }
+
+uint32_t sleep_pending = 0;
+void EXTI15_10_IRQHandler(void)
+{
+	uint32_t PR1 = EXTI->PR1;
+
+	if (gpio_din(BTN_SLEEP)) {
+		while (gpio_din(BTN_SLEEP));
+		if (sleep_pending != 0) {
+			sleep_pending = 0;
+			extern void wakeup(void);
+			wakeup();
+		} else {
+			sleep_pending |= 1;
+		}
+		return;
+	}
+
+	EXTI->PR1 |= PR1;
+}
+
diff --git a/src/main.c b/src/main.c
index a86db6a..4380eae 100644
--- a/src/main.c
+++ b/src/main.c
@@ -21,6 +21,7 @@
 #include <clock.h>

 #include <display.h>

 #include <display_draw.h>

+#include <fat32.h>

 #include <flash.h>

 #include <gpio.h>

 #include <heap.h>

@@ -30,6 +31,7 @@
 #include <it/parser.h>

 #include <random.h>

 #include <script.h>

+#include <sdcard.h>

 #include <serial.h>

 #include <stm32l476xx.h>

 #include <string.h>

@@ -60,7 +62,7 @@ int main(void)
 	keypad_init();

 	flash_init();

 

-	gpio_mode(GPIOA, 5, OUTPUT);

+	//gpio_mode(GPIOA, 5, OUTPUT); // taken by sd

 

 	// enable FPU

 	SCB->CPACR |= (0xF << 20);

@@ -71,9 +73,25 @@ int main(void)
 	while (1);

 }

 

+void sleep(void)

+{

+	dsp_sleep();

+	*((uint32_t *)0xE000ED10) |= 4; // SLEEPDEEP

+	PWR->CR1 |= 2;

+	asm("wfi");

+}

+

+void wakeup(void)

+{

+	clock_init();

+	dsp_wakeup();

+}

+

 void kmain(void)

 {

 	dsp_init();

+	sd_init();

+	fat_find();

 	dsp_cursoron();

 	keypad_start();

 

@@ -81,30 +99,37 @@ void kmain(void)
 	task_start(task_status, 512);

 

 	while (1) {

-		gpio_dout(GPIOA, 5, 1);

-		delay(250);

-		gpio_dout(GPIOA, 5, 0);

-		delay(250);

+		extern uint32_t sleep_pending;

+		if (sleep_pending != 0) {

+			sleep();

+			while (sleep_pending)

+				delay(1);

+		}

+		//gpio_dout(GPIOA, 5, 1);

+		//delay(250);

+		//gpio_dout(GPIOA, 5, 0);

+		delay(100);

 	}

 }

 

 instance *load_program(const char *name)

 {

 	// load file

-	char *s = initrd_readfile(name);

-	if (s == 0) {

+	file_t *file = fat_findfile(name);

+	if (file == 0) {

 		dsp_puts("can't find ");

 		dsp_puts(name);

 		goto fail;

 	}

 

+	char *s = fat_readfile(file);

 	instance *it = inewinstance();

 	script_loadlib(it);

 

 	// read in, parse into script code

 	char *linebuf = (char *)malloc(120);

 	uint32_t i = 0, prev = 0, lc;

-	uint32_t size = initrd_filesize(name);

+	uint32_t size = file->size;

 	int ret = 0;

 	while (i < size) {

 		for (; s[i] != '\n' && s[i] != '\0'; i++);

@@ -121,6 +146,8 @@ instance *load_program(const char *name)
 		prev = ++i;

 	}

 	free(linebuf);

+	free(s);

+	free(file);

 	return it;

 fail:

 	while (1);

diff --git a/src/script.c b/src/script.c
index 51a3bb7..5ba0c08 100644
--- a/src/script.c
+++ b/src/script.c
@@ -39,9 +39,11 @@
 int script_puts(instance *it);
 int script_putchar(instance *it);
 int script_gets(instance *it);
+int script_getf(instance *it);
 int script_delay(instance *it);
 int script_rect(instance *it);
 int script_ppos(instance *it);
+int script_rpos(instance *it);
 int script_line(instance *it);
 int script_color(instance *it);
 int script_rand(instance *it);
@@ -53,6 +55,8 @@ int script_program(instance *it);
 int script_free(instance *it);
 
 int math_sin(instance *it);
+int math_cos(instance *it);
+int math_tan(instance *it);
 
 void script_loadlib(instance *it)
 {
@@ -61,8 +65,10 @@ void script_loadlib(instance *it)
 	inew_cfunc(it, "print", script_puts);
 	inew_cfunc(it, "putchar", script_putchar);
 	inew_cfunc(it, "gets", script_gets);
+	inew_cfunc(it, "getf", script_getf);
 	inew_cfunc(it, "getkey", script_getkey);
 	inew_cfunc(it, "ppos", script_ppos);
+	inew_cfunc(it, "rpos", script_rpos);
 
 	inew_cfunc(it, "pixel", script_pixel);
 	inew_cfunc(it, "line", script_line);
@@ -78,6 +84,8 @@ void script_loadlib(instance *it)
 	inew_cfunc(it, "freemem", script_free);
 
 	inew_cfunc(it, "sin", math_sin);
+	inew_cfunc(it, "cos", math_cos);
+	inew_cfunc(it, "tan", math_tan);
 }
 
 int math_sin(instance *it)
@@ -88,6 +96,22 @@ int math_sin(instance *it)
 	return 0;
 }
 
+int math_cos(instance *it)
+{
+	variable *n = igetarg(it, 0);
+	variable *v = make_varf(0, cosf(n->value.f));
+	ipush(it, (uint32_t)v);
+	return 0;
+}
+
+int math_tan(instance *it)
+{
+	variable *n = igetarg(it, 0);
+	variable *v = make_varf(0, tanf(n->value.f));
+	ipush(it, (uint32_t)v);
+	return 0;
+}
+
 int script_menu(instance *it)
 {
 	char listbuf[4];
@@ -113,13 +137,15 @@ int script_menu(instance *it)
 	return 0;
 }
 
+#include <fat32.h>
+
 int script_filemenu(instance *it)
 {
 	char listbuf[4];
 	char *fname;
 	strncpy(listbuf, " : \0", 4);
 	dsp_puts("Choose a file: \n");
-	for (unsigned int i = 0; (fname = initrd_getname(i)) != 0; i++) {
+	for (unsigned int i = 0; (fname = /*initrd*/fat_getname(i)) != 0; i++) {
 		listbuf[0] = i + '0';
 		dsp_puts(listbuf);
 		dsp_puts(fname);
@@ -163,6 +189,18 @@ int script_putchar(instance *it)
 	return 0;
 }
 
+int script_getf(instance *it)
+{
+	if (script_gets(it) != 0)
+		return -1;
+
+	variable *s = (variable *)ipop(it);
+	s->value.f = strtof((char *)s->value.p, 0);
+	s->type = NUMBER;
+	ipush(it, (uint32_t)s);
+	return 0;
+}
+
 int script_gets(instance *it)
 {
 	char *s = malloc(64);
@@ -261,8 +299,14 @@ int script_line(instance *it)
 
 int script_ppos(instance *it)
 {
-	dsp_cpos(0, 0);
-	dsp_coff(igetarg_integer(it, 0), igetarg_integer(it, 1));
+	dsp_coff(0, 0);
+	dsp_cpos(igetarg_integer(it, 0), igetarg_integer(it, 1));
+	return 0;
+}
+
+int script_rpos(instance *it)
+{
+	dsp_spos(igetarg_integer(it, 0), igetarg_integer(it, 1));
 	return 0;
 }
 
@@ -305,7 +349,7 @@ extern instance *load_program(const char *name);
 int script_program(instance *it)
 {
 	int initrdOffset = (int)igetarg(it, 0)->value.f;
-	char *name = initrd_getname(initrdOffset);
+	char *name = fat_getname(initrdOffset);
 
 	dsp_rect(0, 0, 480, 300, 0);
 	dsp_cpos(0, 0);
diff --git a/src/sdcard.c b/src/sdcard.c
new file mode 100644
index 0000000..6cf602b
--- /dev/null
+++ b/src/sdcard.c
@@ -0,0 +1,222 @@
+/**
+ * @file sdcard.c
+ * Provides a basic library for accessing an SD card
+ *
+ * Copyright (C) 2018 Clyne Sullivan
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <clock.h>
+#include <gpio.h>
+#include <heap.h>
+#include <sdcard.h>
+#include <string.h>
+
+#define SCK GPIO_PORT(A, 5)
+#define SO  GPIO_PORT(A, 6)
+#define SI  GPIO_PORT(A, 7)
+#define CS  GPIO_PORT(B, 6)
+
+typedef struct {
+	uint8_t cmd;
+	uint32_t arg;
+	uint8_t crc;
+} __attribute__ ((packed)) sdcmd_t;
+
+typedef struct {
+	uint8_t zero    :1;
+	uint8_t param   :1;
+	uint8_t address :1;
+	uint8_t erase   :1;
+	uint8_t crc     :1;
+	uint8_t badcmd  :1;
+	uint8_t ereset  :1;
+	uint8_t idle    :1;
+} __attribute__ ((packed)) r1_t;
+
+void flash_out(uint8_t byte)
+{
+	for (int i = 0; i < 8; i++) {
+		gpio_dout(SI, byte & (1 << (7 - i)));
+		gpio_dout(SCK, 1);
+		gpio_dout(SCK, 0);
+	}
+}
+
+uint8_t flash_in(void)
+{
+	uint8_t byte = 0;
+	for (int i = 0; i < 8; i++) {
+		if (gpio_din(SO))
+			byte |= 1 << (7 - i);
+		gpio_dout(SCK, 1);
+		gpio_dout(SCK, 0);
+	}
+	return byte;
+}
+
+void sd_delay(void)
+{
+	gpio_dout(SI, 1);
+	uint8_t so;
+	int i = 0;
+	do {
+		so = flash_in();
+		if (i < 8)
+			i++;
+	} while (i < 8 || so != 0xFF);
+}
+
+uint8_t sd_send_cmd(uint8_t cmd, uint32_t arg)
+{
+	sdcmd_t cmdp;
+	cmdp.cmd = (cmd & 0x3F) | 0x40;
+	cmdp.arg = arg;
+
+	sd_delay();
+	flash_out(cmdp.cmd);
+	flash_out(cmdp.arg >> 24);
+	flash_out(cmdp.arg >> 16);
+	flash_out(cmdp.arg >> 8);
+	flash_out(cmdp.arg);
+	flash_out(cmd == 8 ? 0x87 : 0x95);
+
+	// wait for a zero
+	gpio_dout(SI, 1);
+	uint8_t r1;
+	do {
+		r1 = flash_in();
+	} while (r1 & 0x80);
+
+	return r1;
+}
+
+void sd_init(void)
+{
+	gpio_mode(SCK, OUTPUT);
+	gpio_mode(SI, OUTPUT);
+	gpio_mode(CS, OUTPUT);
+	gpio_mode(SO, OUTPUT);
+	gpio_speed(SCK, VERYHIGH);
+	gpio_speed(SI, VERYHIGH);
+	gpio_speed(SO, VERYHIGH);
+	gpio_speed(CS, VERYHIGH);
+	gpio_pupd(SCK, PULLUP);
+	gpio_pupd(SI, PULLUP);
+	gpio_pupd(SO, PULLUP);
+	gpio_pupd(CS, PULLUP);
+	gpio_dout(SO, 0);
+	gpio_mode(SO, INPUT);
+	gpio_dout(CS, 1);
+	gpio_dout(SCK, 0);
+	gpio_dout(SI, 1);
+
+	// init? cs and si are high
+	delay(10);
+	sd_delay();
+
+	// pull cs low, send cmd0
+	gpio_dout(CS, 0);
+	uint8_t resp = sd_send_cmd(0, 0);
+	sd_delay();
+	gpio_dout(CS, 1);
+
+	if (resp != 0x01)
+		while (1);
+
+	// do cmd8
+	delay(10);
+	gpio_dout(CS, 0);
+	resp = sd_send_cmd(8, 0x1AA);
+	uint8_t ocr[4];
+	for (int i = 0; i < 4; i++)
+		ocr[i] = flash_in();
+	sd_delay();
+	gpio_dout(CS, 1);
+	(void)ocr;
+
+	// initialize
+	do {
+		// cmd55
+		gpio_dout(CS, 0);
+		resp = sd_send_cmd(55, 0);
+		sd_delay();
+		gpio_dout(CS, 1);
+		delay(10);
+
+		// acmd41
+		gpio_dout(CS, 0);
+		resp = sd_send_cmd(41, 0x40000000);
+		sd_delay();
+		gpio_dout(CS, 1);
+	} while (resp != 0x00);
+
+	// set block length
+	gpio_dout(CS, 0);
+	resp = sd_send_cmd(16, 512);
+	sd_delay();
+	gpio_dout(CS, 1);
+}
+
+uint8_t *sd_read_block(uint8_t *buf, uint32_t lba)
+{
+	if (buf == 0)
+		return 0;
+
+	// send command
+	gpio_dout(CS, 0);
+	if (sd_send_cmd(17, lba) != 0)
+		return 0;
+
+	// wait for block
+	gpio_dout(SI, 1);
+	uint8_t byte;
+	do byte = flash_in();
+	while (byte == 0xFF);
+	if (byte != 0xFE)
+		return 0;
+
+	// get block
+	uint32_t i = 0;
+	for (i = 0; i < 512; i++)
+		buf[i] = flash_in();
+
+	sd_delay();
+	gpio_dout(CS, 1);
+	return buf;
+}
+
+uint8_t *sd_read(uint8_t *buf, uint32_t lba, uint32_t count)
+{
+	if (buf == 0)
+		return 0;
+
+	uint8_t *block_buf = malloc(512);
+	uint32_t i = 0;
+	while (count > 0) {
+		sd_read_block(block_buf, lba);
+		memcpy(buf + i, block_buf, (count < 512) ? count : 512);
+		if (count < 512)
+			count = 0;
+		else
+			count -= 512;
+		i += 512;
+		lba++;
+	}
+
+	free(block_buf);
+	return buf;
+}
+
diff --git a/src/stdlib.c b/src/stdlib.c
index 4714e93..a47fb03 100644
--- a/src/stdlib.c
+++ b/src/stdlib.c
@@ -85,7 +85,6 @@ char *snprintf(char *buf, unsigned int max, const char *format, ...)
 
 float strtof(const char *s, char **endptr)
 {
-	(void)s;
 	(void)endptr;
 
 	float res = 0.0f;
@@ -139,6 +138,12 @@ char *ftostr(char *buf, float f)
 	if (buf == 0)
 		return 0;
 
+	if (f == 0) {
+		buf[0] = '0';
+		buf[1] = '\0';
+		return buf;
+	}
+
 	unsigned int i = 0; // offset
 
 	// strip decimals, convert in reverse