From 177bea75a11bc62915095213c351c8385ea12226 Mon Sep 17 00:00:00 2001
From: "Douglas B. Rumbaugh" <doug@douglasrumbaugh.com>
Date: Mon, 6 Jan 2025 12:23:42 -0500
Subject: Initial commit of cdf program and basic build system

---
 .gitignore    |   5 ++
 Makefile      |   4 +
 include/cdf.h |  40 ++++++++++
 src/cdf.c     | 244 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 293 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 Makefile
 create mode 100644 include/cdf.h
 create mode 100644 src/cdf.c

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..d5d3e26
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,5 @@
+.cache
+compile_commands.json
+bin/*
+build/*
+*.bak
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..0374e62
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,4 @@
+all: bin/cdf
+	
+bin/cdf: src/cdf.c include/cdf.h
+	gcc -std=c23 -Iinclude src/cdf.c -o bin/cdf
diff --git a/include/cdf.h b/include/cdf.h
new file mode 100644
index 0000000..418ffeb
--- /dev/null
+++ b/include/cdf.h
@@ -0,0 +1,40 @@
+/*
+ */
+
+#ifndef H_CDF
+#define H_CDF
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <ctype.h>
+#include <getopt.h>
+#include <string.h>
+#include <stdint.h>
+#include <assert.h>
+
+typedef union {
+  int64_t i;
+  uint64_t u;
+  double d;
+} Number;
+
+typedef struct {
+  Number data;
+  uint64_t count;
+} DistRecord;
+
+static int parse_options(int argc, char*const* argv);
+static void help();
+static int process_data(FILE *file);
+static DistRecord *expand_array(DistRecord *records, size_t *capacity);
+static int read_data_int(DistRecord **records, size_t capacity, FILE *file);
+static int read_data_uint(DistRecord **records, size_t capacity, FILE *file);
+static int read_data_fp(DistRecord **records, size_t capacity, FILE *file);
+static int print_data_fp(DistRecord *records, long double *freqs, size_t cnt);
+static int print_data_int(DistRecord *records, long double *freqs, size_t cnt);
+static int print_data_uint(DistRecord *records, long double *freqs, size_t cnt);
+
+#endif
+
+ 
diff --git a/src/cdf.c b/src/cdf.c
new file mode 100644
index 0000000..7d0bd87
--- /dev/null
+++ b/src/cdf.c
@@ -0,0 +1,244 @@
+/*
+ * 
+ */
+
+
+#include "cdf.h"
+
+/*
+ * Global configuration variables. These are set based on command-line
+ * arguments, and read-only beyond that point.
+ */
+static bool ARG_REVERSE_CDF = false;
+static bool ARG_FP_INPUT = false;
+static bool ARG_UINT_INPUT = false;
+static bool ARG_HELP = false;
+
+static int parse_options(int argc, char*const* argv) {
+  int arg_index = 0;
+  int arg;
+  bool error = false;
+
+  while ((arg = getopt(argc, argv, "frhu")) != -1) {
+    switch (arg) {
+      case 'f':
+        ARG_FP_INPUT = true;
+        break;
+      case 'r':
+        ARG_REVERSE_CDF = true;
+        break;
+      case 'u':
+        ARG_UINT_INPUT = true;
+      case 'h':
+        ARG_HELP = true;
+        break;
+      case '?':
+        if (isprint(optopt)) {
+          fprintf(stderr, "Unknown option `-%c`.\n", optopt);
+        } else {
+          fprintf(stderr, "Unknown option character `\\x%x`.\n", optopt);
+        }
+        error = true;
+        break;
+      default:
+        error = true;
+        break;
+    }
+  }
+
+  if (ARG_UINT_INPUT && ARG_FP_INPUT) {
+    fprintf(stderr, "Error: the -u and -f flags are mutually exclusive.\n");
+    error = true;
+  }
+
+  if (!error) {
+    arg_index = optind;
+  }
+
+  return arg_index;
+}
+
+static void help() {
+  fprintf(stderr, "Usage:\ncdf [-f] [-r] [filename]\n");
+}
+
+static DistRecord *expand_array(DistRecord *records, size_t *capacity) {
+  (*capacity) *= 2;
+  DistRecord *new = realloc(records, *capacity);
+  if (!new) {
+    fprintf(stderr, "ERROR: Memory allocation failed\n");
+    return nullptr;
+  }
+
+  return new;
+}
+
+static int read_data_int(DistRecord **records, size_t capacity, FILE *file) {
+  size_t reccnt = 0;
+  while (fscanf(file, "%ld %ld\n", &(*records + reccnt)->count,
+                &(*records + reccnt)->data.i) != EOF) {
+
+    reccnt++;
+    if (reccnt == capacity) {
+      if (!(*records = expand_array(*records, &capacity))) {
+        return -1;
+      }
+    }
+  }
+
+  return reccnt;
+}
+
+static int read_data_fp(DistRecord **records, size_t capacity, FILE *file) {
+  size_t reccnt = 0;
+  while (fscanf(file, "%ld %lf\n", &(*records + reccnt)->count,
+                &(*records + reccnt)->data.d) != EOF) {
+
+    reccnt++;
+    if (reccnt == capacity) {
+      if (!(*records = expand_array(*records, &capacity))) {
+        return -1;
+      }
+    }
+  }
+
+  return reccnt;
+}
+
+static int read_data_uint(DistRecord **records, size_t capacity, FILE *file) {
+  size_t reccnt = 0;
+  while (fscanf(file, "%ld %ld\n", &(*records + reccnt)->count,
+                &(*records + reccnt)->data.u) != EOF) {
+
+    reccnt++;
+    if (reccnt == capacity) {
+      if (!(*records = expand_array(*records, &capacity))) {
+        return -1;
+      }
+    }
+  }
+
+  return reccnt;
+}
+
+static int print_data_fp(DistRecord *records, long double *freqs, size_t cnt) {
+  for (size_t i=0; i<cnt; i++) {
+    fprintf(stdout, "%Lf\t%lf\n", freqs[i], records[i].data.d);
+  }  
+
+  return 1;
+}
+
+static int print_data_int(DistRecord *records, long double *freqs, size_t cnt) {
+  for (size_t i=0; i<cnt; i++) {
+    fprintf(stdout, "%Lf\t%ld\n", freqs[i], records[i].data.i);
+  }  
+
+  return 1;
+}
+
+static int print_data_uint(DistRecord *records, long double *freqs, size_t cnt) {
+  for (size_t i=0; i<cnt; i++) {
+    fprintf(stdout, "%Lf\t%ld\n", freqs[i], records[i].data.u);
+  }  
+
+  return 1;
+}
+
+static int process_data(FILE *file) {
+  int rc = 1;
+  
+  size_t reccap = 100;
+  DistRecord *records = malloc(reccap*sizeof(DistRecord));
+
+  ssize_t cnt;
+  /* FIXME: this could probably use a type-based macro to collapse the 
+            if statements into a single macro call
+   */
+  if (ARG_FP_INPUT) {
+    cnt = read_data_fp(&records, reccap, file);
+  } else if (ARG_UINT_INPUT) {
+    cnt = read_data_uint(&records, reccap, file);
+  } else {
+    cnt = read_data_int(&records, reccap, file);
+  }
+
+  /* propogate the error */
+  if (cnt == -1) {
+    rc = 0;
+    goto free_records;
+  }
+
+  /* calculate total sum of counts */
+  uint64_t total_count = 0;
+  for (size_t i=0; i<cnt; i++) {
+    total_count += records[i].count;
+  }
+
+  /* calculate relative frequency for each item */
+  long double *freqs = malloc(sizeof(long double) * cnt);
+  if (!freqs) {
+    fprintf(stderr, "ERROR: memory allocation failure.\n");
+    goto free_freqs;
+  }
+
+  for (size_t i=0; i<cnt; i++) {
+    freqs[i] = (long double) (records[i].count) / (long double) (total_count);
+  }
+
+  if (ARG_FP_INPUT) {
+    rc = print_data_fp(records, freqs, cnt);
+  } else if (ARG_UINT_INPUT) {
+    rc = print_data_uint(records, freqs, cnt);
+  } else {
+    rc = print_data_int(records, freqs, cnt);
+  }
+  
+free_freqs:
+  free(freqs);
+
+free_records:
+  free(records);
+
+process_data_end:
+  return rc;
+}
+
+
+int main(int argc, char **argv) {
+  int rc = EXIT_SUCCESS;
+  int file_index = 0;
+  if (!(file_index = parse_options(argc, argv))) {
+    help();
+    rc = EXIT_FAILURE;
+    goto program_exit;
+  }
+
+  /* if the -h argument is supplied, print usage and exit successfully */
+  if (ARG_HELP) {
+    help();
+    goto program_exit;
+  }
+
+  /* open the input file, if one is specified, otherwise default to stdin */
+  FILE *input_file;
+  if (file_index < argc && strcmp(argv[file_index], "-") != 0) {
+    if (!(input_file = fopen(argv[file_index], "r"))) {
+      fprintf(stderr, "Error: Unable to open input file %s\n", argv[file_index]);
+      rc = EXIT_FAILURE;
+      goto program_exit;
+    }
+  } else {
+    input_file = stdin;
+  }
+
+  if (!process_data(input_file)) {
+    rc = EXIT_FAILURE;
+  }
+
+close_file:
+  fclose(input_file);
+
+program_exit:
+  exit(rc);
+}
-- 
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