feat: add more user programs

5 files changed, 308 insertions, 63 deletions

diff --git a/user/calc.c b/user/calc.c
new file mode 100644
index 0000000..2d0e3f8
--- /dev/null
+++ b/user/calc.c
@@ -0,0 +1,78 @@
+#include "user.h"
+
+static int is_digit(char character)
+{
+    return character >= '0' && character <= '9';
+}
+
+void _start(void)
+{
+    put("calc, e.g. 3 + 4 * 2 (left to right), empty line quits\n");
+
+    char line[128];
+    for (;;)
+    {
+        put("> ");
+        int length = read_line(line, 128);
+        put("\n");
+        if (length == 0)
+            break;
+
+        long accumulator = 0;
+        char operator = '+';
+        int valid = 1;
+        int saw_number = 0;
+        int position = 0;
+        while (position < length)
+        {
+            char character = line[position];
+            if (character == ' ')
+            {
+                position++;
+                continue;
+            }
+            if (is_digit(character))
+            {
+                long value = 0;
+                while (position < length && is_digit(line[position]))
+                    value = value * 10 + (line[position++] - '0');
+                if (operator == '+')
+                    accumulator += value;
+                else if (operator == '-')
+                    accumulator -= value;
+                else if (operator == '*')
+                    accumulator *= value;
+                else if (operator == '/' || operator == '%')
+                {
+                    if (value == 0)
+                    {
+                        put("divide by zero\n");
+                        valid = 0;
+                        break;
+                    }
+                    accumulator = (operator == '/') ? accumulator / value : accumulator % value;
+                }
+                saw_number = 1;
+            }
+            else if (character == '+' || character == '-' || character == '*'
+                     || character == '/' || character == '%')
+            {
+                operator = character;
+                position++;
+            }
+            else
+            {
+                put("bad character\n");
+                valid = 0;
+                break;
+            }
+        }
+        if (valid && saw_number)
+        {
+            put("= ");
+            put_int(accumulator);
+            put("\n");
+        }
+    }
+    sys_exit(0);
+}
diff --git a/user/hexview.c b/user/hexview.c
new file mode 100644
index 0000000..f2425e1
--- /dev/null
+++ b/user/hexview.c
@@ -0,0 +1,91 @@
+// hexview, a ring 3 program that dumps a file from the revel fs. nav is n/p/q
+// since the keyboard only gives us decoded ascii, no arrow keys yet
+
+#include "user.h"
+
+static const char HEX[] = "0123456789abcdef";
+
+static void put_hex8(unsigned char byte)
+{
+    char digits[2] = { HEX[byte >> 4], HEX[byte & 15] };
+    sys_write(digits, 2);
+}
+
+static void put_hex32(unsigned long value)
+{
+    char digits[8];
+    for (int nibble = 0; nibble < 8; nibble++)
+        digits[nibble] = HEX[(value >> ((7 - nibble) * 4)) & 15];
+    sys_write(digits, 8);
+}
+
+#define PAGE 256
+#define COLS 16
+
+void _start(void)
+{
+    put("hexview, type a filename\nfile: ");
+    char name[64];
+    read_line(name, 64);
+    put("\n");
+
+    long size = sys_fs_size(name);
+    if (size < 0)
+    {
+        put("no such file\n");
+        sys_exit(1);
+    }
+
+    unsigned long offset = 0;
+    char buffer[PAGE];
+    for (;;)
+    {
+        long count = sys_fs_read(name, offset, buffer, PAGE);
+
+        put("--- ");
+        put(name);
+        put(" @ 0x");
+        put_hex32(offset);
+        put(" / 0x");
+        put_hex32((unsigned long)size);
+        put(" ---\n");
+
+        for (long row = 0; row < count; row += COLS)
+        {
+            put_hex32(offset + (unsigned long)row);
+            put(": ");
+            for (int column = 0; column < COLS; column++)
+            {
+                if (row + column < count)
+                {
+                    put_hex8((unsigned char)buffer[row + column]);
+                    sys_write(" ", 1);
+                }
+                else
+                    put("   ");
+            }
+            put(" ");
+            for (int column = 0; column < COLS && row + column < count; column++)
+            {
+                char character = buffer[row + column];
+                if (character >= 32 && character < 127)
+                    sys_write(&character, 1);
+                else
+                    sys_write(".", 1);
+            }
+            put("\n");
+        }
+
+        put("[n]ext [p]rev [q]uit > ");
+        char key = (char)sys_read();
+        put("\n");
+        if (key == 'q')
+            break;
+        if (key == 'n' && offset + PAGE < (unsigned long)size)
+            offset += PAGE;
+        if (key == 'p' && offset >= PAGE)
+            offset -= PAGE;
+    }
+
+    sys_exit(0);
+}
diff --git a/user/primes.c b/user/primes.c
new file mode 100644
index 0000000..49c545a
--- /dev/null
+++ b/user/primes.c
@@ -0,0 +1,42 @@
+#include "user.h"
+
+void _start(void)
+{
+    put("primes up to N, enter N (empty line quits)\n");
+    char line[32];
+    for (;;)
+    {
+        put("> ");
+        int length = read_line(line, 32);
+        put("\n");
+        if (length == 0)
+            break;
+
+        long limit = 0;
+        for (int position = 0; position < length; position++)
+            if (line[position] >= '0' && line[position] <= '9')
+                limit = limit * 10 + (line[position] - '0');
+
+        int count = 0;
+        for (long candidate = 2; candidate <= limit; candidate++)
+        {
+            int prime = 1;
+            for (long divisor = 2; divisor * divisor <= candidate; divisor++)
+                if (candidate % divisor == 0)
+                {
+                    prime = 0;
+                    break;
+                }
+            if (prime)
+            {
+                put_int(candidate);
+                put(" ");
+                count++;
+            }
+        }
+        put("\n");
+        put_int(count);
+        put(" primes\n");
+    }
+    sys_exit(0);
+}
diff --git a/user/program.c b/user/program.c
deleted file mode 100644
index 65621f5..0000000
--- a/user/program.c
+++ /dev/null
@@ -1,63 +0,0 @@
-static long sys_write(const char* buffer, unsigned long buffer_length)
-{
-    long ret;
-    __asm__ volatile("int $0x80" : "=a"(ret) : "a"(1L), "D"(buffer), "S"(buffer_length) : "memory");
-    return ret;
-}
-
-static long sys_read(void)
-{
-    long ret;
-    __asm__ volatile("int $0x80" : "=a"(ret) : "a"(2L) : "memory");
-    return ret;
-}
-
-static void sys_exit(long code)
-{
-    __asm__ volatile("int $0x80" : : "a"(0L), "D"(code) : "memory");
-    for (;;);
-}
-
-static void put(const char* string)
-{
-    unsigned long n = 0;
-    while (string[n])
-        n++;
-    sys_write(string, n);
-}
-
-void _start(void)
-{
-    put("what's your name? ");
-    char name[64];
-    int name_length = 0;
-
-    for (;;)
-    {
-        char character = (char)sys_read();
-        if (character == '\n')
-            break;
-
-        if (character == '\b')
-        {
-            if (name_length > 0)
-            {
-                name_length--;
-                sys_write("\b \b", 3);
-            }
-
-            continue;
-        }
-
-        if (name_length < 63)
-        {
-            name[name_length++] = character;
-            sys_write(&character, 1);
-        }
-    }
-
-    put("\noue va te faire foutre ");
-    sys_write(name, name_length);
-    put("\n");
-    sys_exit(0);
-}
diff --git a/user/user.h b/user/user.h
new file mode 100644
index 0000000..676326b
--- /dev/null
+++ b/user/user.h
@@ -0,0 +1,97 @@
+// shared syscall stubs + tiny helpers for revel ring 3 programs
+
+static long sys_write(const char* buffer, unsigned long length)
+{
+    long result;
+    __asm__ volatile("int $0x80" : "=a"(result) : "a"(1L), "D"(buffer), "S"(length) : "memory");
+    return result;
+}
+
+static long sys_read(void)
+{
+    long result;
+    __asm__ volatile("int $0x80" : "=a"(result) : "a"(2L) : "memory");
+    return result;
+}
+
+static void sys_exit(long code)
+{
+    __asm__ volatile("int $0x80" : : "a"(0L), "D"(code) : "memory");
+    for (;;);
+}
+
+static long sys_fs_size(const char* name)
+{
+    long result;
+    __asm__ volatile("int $0x80" : "=a"(result) : "a"(4L), "D"(name) : "memory");
+    return result;
+}
+
+static long sys_fs_read(const char* name, unsigned long offset, char* buffer, unsigned long length)
+{
+    long result;
+    __asm__ volatile("int $0x80"
+                     : "=a"(result)
+                     : "a"(5L), "D"(name), "S"(offset), "d"(buffer), "c"(length)
+                     : "memory");
+    return result;
+}
+
+static void put(const char* string)
+{
+    unsigned long length = 0;
+    while (string[length])
+        length++;
+    sys_write(string, length);
+}
+
+static int read_line(char* buffer, int max_length)
+{
+    int length = 0;
+    for (;;)
+    {
+        char character = (char)sys_read();
+        if (character == '\n')
+            break;
+        if (character == '\b')
+        {
+            if (length > 0)
+            {
+                length--;
+                sys_write("\b \b", 3);
+            }
+            continue;
+        }
+        if (length < max_length - 1)
+        {
+            buffer[length++] = character;
+            sys_write(&character, 1);
+        }
+    }
+    buffer[length] = 0;
+    return length;
+}
+
+static void put_int(long value)
+{
+    char buffer[21];
+    int length = 0;
+    int negative = value < 0;
+    unsigned long magnitude = negative ? (unsigned long)(-value) : (unsigned long)value;
+    if (magnitude == 0)
+        buffer[length++] = '0';
+    while (magnitude > 0)
+    {
+        buffer[length++] = (char)('0' + magnitude % 10);
+        magnitude /= 10;
+    }
+    if (negative)
+        buffer[length++] = '-';
+    for (int left = 0, right = length - 1; left < right; left++, right--)
+    {
+        char swap = buffer[left];
+        buffer[left] = buffer[right];
+        buffer[right] = swap;
+    }
+    sys_write(buffer, length);
+}