plotting complete - ploot - simple plotting tools
HTML git clone git://bitreich.org/ploot git://enlrupgkhuxnvlhsf6lc3fziv5h2hhfrinws65d7roiv6bfj7d652fid.onion/ploot
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DIR Files
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DIR Tags
DIR README
DIR LICENSE
---
DIR commit df6b2deeefb42f4102a9bba819e7d06d15a3aebf
DIR parent 980b7ae7316438998c953a8e098d894aec001c57
HTML Author: Josuah Demangeon <mail@josuah.net>
Date: Tue, 1 May 2018 18:35:48 +0200
plotting complete
Diffstat:
M Makefile | 5 +++--
M ffdraw.c | 56 +++++++++++++++++++++++--------
M ffdraw.h | 27 +++++++++++++++++++++------
M main.c | 295 +++++++++++++++++++++++--------
M ploot.c | 34 ++++++++++++++++----------------
5 files changed, 308 insertions(+), 109 deletions(-)
---
DIR diff --git a/Makefile b/Makefile
@@ -1,13 +1,14 @@
CFLAGS = -Wall -Wextra -Werror -std=c89 -pedantic -D_POSIX_C_SOURCE=200809L
+LDFLAGS = -static
SRC = main.c ffdraw.c font_14x7.c
-
OBJ = $(SRC:.c=.o)
+LIB = -lm
all:x ploot
ploot: $(OBJ)
- ${CC} -static -o $@ $(OBJ)
+ ${CC} $(LDFLAGS) -o $@ $(OBJ) $(LIB)
install:x ploot
mkdir -p ${PREFIX}/bin
DIR diff --git a/ffdraw.c b/ffdraw.c
@@ -12,27 +12,25 @@
#include "ffdraw.h"
-#define WIDTH 100
-#define HEIGHT 100
-
-Color buffer[WIDTH * HEIGHT];
-
/*
* Convert (x,y) coordinates to (row,col) for printing into the buffer.
* The buffer only contain one number, so the coordinate is a single integer:
* width * x + y.
+ * The coordinates are shifted by offx and offy to permit relative coordinates.
*/
void
-ffdraw_pixel(Canvas *can, Color col,
+ffdraw_pixel(Canvas *can, Color *col,
int x, int y)
{
- if (x >= can->h || y >= can->w)
+ x += can->x;
+ y += can->y;
+ if (x < 0 || x >= can->h || y < 0 || y >= can->w)
return;
memcpy(can->b + can->w * (can->h - 1 - x) + y, col, sizeof(*can->b));
}
void
-ffdraw_rectangle(Canvas *can, Color col,
+ffdraw_rectangle(Canvas *can, Color *col,
int x1, int y1,
int x2, int y2)
{
@@ -50,7 +48,7 @@ ffdraw_rectangle(Canvas *can, Color col,
* From Bresenham's line algorithm and dcat's tplot.
*/
void
-ffdraw_line(Canvas *can, Color col,
+ffdraw_line(Canvas *can, Color *col,
int x0, int y0,
int x1, int y1)
{
@@ -81,18 +79,18 @@ ffdraw_line(Canvas *can, Color col,
}
/*
- * Draw a coloured glyph from font f centerd on x, y
+ * Draw a coloured glyph from font f centered on x.
*/
void
-ffdraw_char(Canvas *can, Color col, char c, Font *f,
+ffdraw_char(Canvas *can, Color *col, char c, Font *f,
int x, int y)
{
int xf, yf;
if (c & 0x80)
c = '\0';
+
x -= f->h / 2;
- y -= f->w / 2;
for (xf = 0; xf < f->h; xf++)
for (yf = 0; yf < f->w; yf++)
@@ -104,15 +102,45 @@ ffdraw_char(Canvas *can, Color col, char c, Font *f,
* Draw a left aligned string without wrapping it.
*/
void
-ffdraw_str(Canvas *can, Color col, char *s, Font *f,
+ffdraw_str_left(Canvas *can, Color *col, char *s, Font *f,
int x, int y)
{
for (; *s != '\0'; y += f->w, s++)
ffdraw_char(can, col, *s, f, x, y);
}
+/*
+ * Draw a center aligned string without wrapping it.
+ */
+void
+ffdraw_str_center(Canvas *can, Color *col, char *s, Font *f,
+ int x, int y)
+{
+ y -= f->w * strlen(s) / 2;
+ ffdraw_str_left(can, col, s, f, x, y);
+}
+
+/*
+ * Draw a right aligned string without wrapping it.
+ */
+void
+ffdraw_str_right(Canvas *can, Color *col, char *s, Font *f,
+ int x, int y)
+{
+ y -= f->w * strlen(s);
+ ffdraw_str_left(can, col, s, f, x, y);
+}
+
void
-ffdraw_fill(Canvas *can, Color col)
+ffdraw_fill(Canvas *can, Color *col)
{
+ int x, y;
+
+ x = can->x; can->x = 0;
+ y = can->y; can->y = 0;
+
ffdraw_rectangle(can, col, 0, 0, can->h - 1, can->w - 1);
+
+ can->x = x;
+ can->y = y;
}
DIR diff --git a/ffdraw.h b/ffdraw.h
@@ -1,3 +1,5 @@
+#include <time.h>
+
#define MIN(x, y) ((x) < (y) ? (x) : (y))
#define MAX(x, y) ((x) > (y) ? (x) : (y))
@@ -7,6 +9,8 @@ typedef struct {
int w; /* width */
int h; /* height */
Color *b; /* buffer */
+ int x; /* x offset */
+ int y; /* x offset */
} Canvas;
typedef struct {
@@ -15,10 +19,21 @@ typedef struct {
char *b[128]; /* buffer */
} Font;
+typedef struct {
+ Color col; /* for drawing the curve and the legend */
+/* time_t *t; / * array of timestamps */
+ double *v; /* array of values */
+ int n; /* number of values */
+ time_t step;
+ char *name; /* for the legend */
+} Vlist;
+
/* ffdraw.c */
-void ffdraw_pixel (Canvas *, Color, int, int);
-void ffdraw_rectangle(Canvas *, Color, int, int, int, int);
-void ffdraw_line (Canvas *, Color, int, int, int, int);
-void ffdraw_char (Canvas *, Color, char, Font *, int, int);
-void ffdraw_str (Canvas *, Color, char *, Font *, int, int);
-void ffdraw_fill (Canvas *, Color);
+void ffdraw_pixel (Canvas *, Color *, int, int);
+void ffdraw_rectangle(Canvas *, Color *, int, int, int, int);
+void ffdraw_line (Canvas *, Color *, int, int, int, int);
+void ffdraw_char (Canvas *, Color *, char, Font *, int, int);
+void ffdraw_str_left(Canvas *, Color *, char *, Font *, int, int);
+void ffdraw_str_center(Canvas *, Color *, char *, Font *, int, int);
+void ffdraw_str_right(Canvas *, Color *, char *, Font *, int, int);
+void ffdraw_fill (Canvas *, Color *);
DIR diff --git a/main.c b/main.c
@@ -1,134 +1,289 @@
#include <arpa/inet.h>
-#include <stdlib.h>
#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
#include <time.h>
+#include <math.h>
+
#include "ffdraw.h"
#include "font_14x7.h"
+#define ABS(x) ((x) < 0 ? -(x) : (x))
+#define LEN(x) (sizeof(x) / sizeof(*x))
+
+/*
+ * Sizes and positions:
+ *
+ * Title on the first row legend
+ * y ^ here
+ * label |- + - + - + - + - with
+ * here |- + - + - + - + - the
+ * +--+---+---+---+--> full
+ * x label here height
+ */
+
+#define MARGIN 4
+
#define FONT_H 14
#define FONT_W 7
-/* as you see, no css skills needed */
+#define TITLE_X (IMAGE_H - TITLE_H)
+#define TITLE_Y (XLABEL_W)
+#define TITLE_H (FONT_H * 2)
+#define TITLE_W (PLOT_W)
+
+#define XLABEL_X (PLOT_X)
+#define XLABEL_Y (0)
+#define XLABEL_H (PLOT_H)
+#define XLABEL_W (FONT_W * 9 + MARGIN)
-#define MARGIN 2
+#define YLABEL_X (0)
+#define YLABEL_Y (PLOT_Y)
+#define YLABEL_H (FONT_H * 2)
+#define YLABEL_W (PLOT_W)
+
+#define PLOT_X (YLABEL_H)
+#define PLOT_Y (XLABEL_W)
+#define PLOT_W 700
+#define PLOT_H 200
+
+#define LEGEND_X (YLABEL_H)
+#define LEGEND_Y (IMAGE_W - LEGEND_W)
+#define LEGEND_W (FONT_W + 150 + FONT_W)
+#define LEGEND_H (PLOT_H)
+
+#define IMAGE_H (TITLE_H + PLOT_H + YLABEL_H)
+#define IMAGE_W (XLABEL_W + PLOT_W + LEGEND_W)
+
+Color buffer[IMAGE_W * IMAGE_H];
+
+Color c_axis = { 0xffff, 0xffff, 0xffff, 0xfff };
+Font *font = &font_14x7;
-/* height */
+int
+ffplot_t2y(time_t t, time_t tmin, time_t tmax)
+{
+ return (t - tmin) * PLOT_W / (tmax - tmin);
+}
-#define TITLE_H (MARGIN + FONT_H + MARGIN)
-#define PLOT_H 100
-#define XLABEL_H (MARGIN + FONT_H + MARGIN)
+int
+ffplot_v2x(double v, double vmin, double vmax)
+{
+ return (v - vmin) * PLOT_H / (vmax - vmin);
+}
-#define IMAGE_H (TITLE_H + PLOT_H + XLABEL_H)
+/*
+ * Set 'str' to a human-readable form of 'num' with always a width of 8 (+ 1
+ * the '\0' terminator). Buffer overflow is ensured not to happen due to the
+ * max size of a double. Return the exponent.
+ */
+int
+humanize(char *str, double val)
+{
+ int exp, precision;
+ char label[] = { '\0', 'M', 'G', 'T', 'E' };
-#define TITLE_MAX (IMAGE_H)
-#define TITLE_MIN (IMAGE_H - TITLE_H)
-#define PLOT_X_MAX (IMAGE_H - TITLE_H)
-#define PLOT_X_MIN (XLABEL_H)
-#define XLABEL_MAX (XLABEL_H)
-#define XLABEL_MIN (0)
+ for (exp = 0; ABS(val) > 1000; exp++)
+ val /= 1000;
-/* width */
+ precision = (ABS(val) < 10) ? 2 : (ABS(val) < 100) ? 1 : 0;
+ precision += (exp == 0);
-#define YLABEL_W (MARGIN + 20 + MARGIN)
-#define PLOT_W 500
-#define LEGEND_W (MARGIN + 70 + MARGIN)
+ snprintf(str, 9, "%+.*f %c", precision, val, label[exp]);
+ str[8] = '\0';
+ if (val >= 0)
+ str[0] = ' ';
-#define IMAGE_W (YLABEL_W + PLOT_W + LEGEND_W)
+ return exp * 3;
+}
-#define LEGEND_MAX (IMAGE_W)
-#define LEGEND_MIN (IMAGE_W - LEGEND_W)
-#define PLOT_Y_MAX (IMAGE_W - LEGEND_W)
-#define PLOT_Y_MIN (YLABEL_W)
-#define YLABEL_MAX (YLABEL_W)
-#define YLABEL_MIN (0)
+void
+ffplot_xaxis(Canvas *can, Color *label, Color *grid,
+ double vmin, double vmax, double vstep)
+{
+ double v;
+ int x;
+ char str[8 + 1];
-#define MID(x, y) ((x - y) / 2)
+ for (v = vmax - fmod(vmax, vstep); v >= vmin; v -= vstep) {
+ x = ffplot_v2x(v, vmin, vmax);
-Color buffer[IMAGE_W * IMAGE_H];
+ ffdraw_line(can, grid,
+ x, XLABEL_W,
+ x, XLABEL_W + PLOT_W);
-Color c_axis = { 0xffff, 0xffff, 0xffff, 0xfff };
-Font *font = &font_14x7;
+ humanize(str, v);
+ ffdraw_str_right(can, label, str, font,
+ x, XLABEL_W - MARGIN);
+ }
+}
void
-ffplot_xaxis(Canvas *can, Color label, Color grid, time_t tmax, time_t tstep)
+ffplot_yaxis(Canvas *can, Color *label, Color *grid,
+ time_t tmin, time_t tmax, time_t tstep)
{
time_t t;
- int y, ystep;
+ int y;
char str[sizeof("YYYY/MM/DD")], *fmt;
- if (tstep < 3600) {
- fmt = " %H:%M:%S ";
- ystep = sizeof(" HH:MM:SS ") * FONT_W;
- } else {
- fmt = " %Y/%m/%d ";
- ystep = sizeof(" YYYY/MM/DD ") * FONT_W;
- }
+ fmt = (tstep < 3600 * 24) ? " %H:%M:%S " : " %Y/%m/%d ";
- t = tmax % tstep;
- y = PLOT_Y_MAX + PLOT_W % ystep - ystep;
+ for (t = tmax - tmax % tstep; t >= tmin; t -= tstep) {
+ y = ffplot_t2y(t, tmin, tmax);
- while (y > PLOT_Y_MIN) {
- strftime(str, sizeof(str), fmt, localtime(&t));
- ffdraw_str(can, label, str, font,
- XLABEL_MIN + XLABEL_H / 2, y - ystep / 2 + FONT_W);
ffdraw_line(can, grid,
- PLOT_X_MIN, y,
- PLOT_X_MAX, y);
- y -= ystep;
- t -= tstep;
+ YLABEL_H, y,
+ YLABEL_H + PLOT_H, y);
+
+ strftime(str, sizeof(str), fmt, localtime(&t));
+ ffdraw_str_center(can, label, str, font,
+ YLABEL_H / 2, y);
}
}
void
-ffplot_(Canvas *can)
+ffplot_title(Canvas *can,
+ Color *ct, char *title,
+ Color *cu, char *unit)
{
- (void)can;
+ ffdraw_str_left(can, ct, title, font,
+ TITLE_H / 2, 0);
+ ffdraw_str_right(can, cu, unit, font,
+ TITLE_H / 2, TITLE_W);
}
void
-ffplot_graph(Canvas *can)
+ffplot_graph(Canvas *can, Vlist *v,
+ double vmin, double vmax,
+ time_t tmin, time_t tmax)
{
- (void)can;
+ time_t t;
+ double *vp;
+ int x, y, n, xlast, ylast, first;
+
+ first = 1;
+ t = tmin;
+ for (vp = v->v, n = v->n; n-- > 0; n--, vp++) {
+ x = ffplot_v2x(*vp, vmin, vmax);
+ y = ffplot_t2y(t, tmin, tmax);
+
+ if (!first)
+ ffdraw_line(can, &v->col, xlast, ylast, x, y);
+
+ xlast = x;
+ ylast = y;
+ t += v->step;
+ first = 0;
+ }
}
void
-ffplot_legend(Canvas *can)
+ffplot_plot(Canvas *can, Vlist **v,
+ double vmin, double vmax,
+ time_t tmin, time_t tmax)
{
- (void)can;
+ for (; *v != NULL; v++)
+ ffplot_graph(can, *v, vmin, vmax, tmin, tmax);
}
-static void
-ffdraw(Canvas *can)
+void
+ffplot_legend(Canvas *can, Color *label_fg, Vlist **v)
{
- Color col1 = { 0x2222, 0x2222, 0x2222, 0xffff };
- Color label = { 0x3333, 0xffff, 0x8888, 0xffff };
- Color grid = { 0x4444, 0x4444, 0x4444, 0xffff };
+ int n, x, y;
- ffdraw_fill(can, col1);
- ffplot_xaxis(can, label, grid, 3600 * 24 * 30, 360);
-/*
- ffdraw_line(can, col2, 49,1,9,79);
- ffdraw_str(can, col2, "R\\S`T'UaVbWcYdZe\nfghb\tjoi\rklmnopqrstuvwxyz{|}", font, 44, 10);
-*/
+ for (n = 0; *v != NULL; v++, n++) {
+ x = LEGEND_H - n * (FONT_H + MARGIN) - FONT_H / 2;
+
+ y = MARGIN + FONT_W;
+ ffdraw_str_left(can, &(*v)->col, "\1", font, x, y);
+
+ y += FONT_W * 2;
+ ffdraw_str_left(can, label_fg, (*v)->name, font, x, y);
+ }
+}
+
+void
+ffdraw(Canvas *can, char *title, char *units, Vlist **vlistv,
+ double vmin, double vmax, double vstep,
+ time_t tmin, time_t tmax, time_t tstep)
+{
+ Color plot_bg = { 0x2222, 0x2222, 0x2222, 0xffff };
+ Color grid_bg = { 0x2929, 0x2929, 0x2929, 0xffff };
+ Color grid_fg = { 0x3737, 0x3737, 0x3737, 0xffff };
+ Color label_fg = { 0x8888, 0x8888, 0x8888, 0xffff };
+ Color title_fg = { 0xdddd, 0xdddd, 0xdddd, 0xffff };
+
+ can->x = 0;
+ can->y = 0;
+ ffdraw_fill(can, &plot_bg);
+
+ can->x = PLOT_X;
+ can->y = PLOT_Y;
+ ffdraw_rectangle(can, &grid_bg, 0, 0, PLOT_H, PLOT_W);
+
+ can->x = YLABEL_X;
+ can->y = YLABEL_Y;
+ ffplot_yaxis(can, &label_fg, &grid_fg, tmin, tmax, tstep);
+
+ can->x = XLABEL_X;
+ can->y = XLABEL_Y;
+ ffplot_xaxis(can, &label_fg, &grid_fg, vmin, vmax, vstep);
+
+ can->x = TITLE_X;
+ can->y = TITLE_Y;
+ ffplot_title(can, &title_fg, title, &label_fg, units);
+
+ can->x = PLOT_X;
+ can->y = PLOT_Y;
+ ffplot_plot(can, vlistv, vmin, vmax, tmin, tmax);
+
+ can->x = LEGEND_X;
+ can->y = LEGEND_Y;
+ ffplot_legend(can, &label_fg, vlistv);
}
int
main(void)
{
+ Canvas can = { IMAGE_W, IMAGE_H, buffer, 0, 0 };
+ double v1[] = { 0.1, 30, -3, 42, 559, 343, 10, 345, 0 };
+ double v2[] = { 30, -3, 42, 559, 343, 10, 345, 0, 0.3 };
+ double v3[] = { 0, 0.3, 30, -3, 42, 5, 43, 345, 0, 10,
+ 0.3, 30, -3, 42, 59, 33, 35, 0, 40, 0.3, 30,
+ 0.3, 30, -3, 42, 55, 3, 5, 0, 100, 0.3, 30,
+ 95, 43, 45, 0, 40, 0.3, 30, 0.3, 30, -3, 42,
+ 0.3, 30, -3, 42, 5, 43, 3, 0, 100, 0.3, 30,
+ 0.3, 30, -3, 42, 59, 43, 45, 0, 4, 0.3, 30,
+ -3, 42, 559, 343, 45, 0, 10 };
+ Vlist vl1 = { { 0x0000, 0xffff, 0xdddd, 0xffff }, NULL, LEN(v1), 500, "available ravens" };
+ Vlist vl2 = { { 0xffff, 0x9999, 0x4444, 0xffff }, NULL, LEN(v2), 500, "used ravens" };
+ Vlist vl3 = { { 0x1111, 0xffff, 0x5555, 0xffff }, NULL, LEN(v3), 57, "free ravens" };
+ Vlist *vlistv[] = { NULL, NULL, NULL, NULL };
+ double vmin, vmax, vstep;
+ time_t tmin, tmax, tstep;
uint32_t w, h;
- Canvas can;
- can.b = buffer;
- can.w = IMAGE_W;
- can.h = IMAGE_H;
+ vlistv[0] = &vl1; vl1.v = v1;
+ vlistv[1] = &vl2; vl2.v = v2;
+ vlistv[2] = &vl3; vl3.v = v3;
+ vlistv[3] = NULL;
+
+ vmin = -30; vmax = 700; vstep = 120;
+ tmin = 0; tmax = 2000; tstep = 300;
+
+ ffdraw(&can, "Council of the ravens", "(feather per second)", vlistv,
+ vmin, vmax, vstep,
+ tmin, tmax, tstep);
+
w = htonl(IMAGE_W);
h = htonl(IMAGE_H);
+
fputs("farbfeld", stdout);
fwrite(&w, sizeof(w), 1, stdout);
fwrite(&h, sizeof(h), 1, stdout);
- ffdraw(&can);
fwrite(can.b, IMAGE_W * IMAGE_H, sizeof(*can.b), stdout);
+
return 0;
}
DIR diff --git a/ploot.c b/ploot.c
@@ -17,7 +17,7 @@
char *argv0;
/*
-** Add `val' at the current position `pos' of the `ring' buffer and set pos to
+** Add 'val' at the current position 'pos' of the 'ring' buffer and set pos to
** the next postion.
*/
#define RING_ADD(rbuf, len, pos, val) \
@@ -27,8 +27,8 @@ do { \
} while (0)
/*
-** Copy the ring buffer `rbuf' content with current position `pos' into the
-** buffer `buf'. Both buffer of length `len'.
+** Copy the ring buffer 'rbuf' content with current position 'pos' into the
+** buffer 'buf'. Both buffer of length 'len'.
*/
#define RING_COPY(buf, rbuf, len, pos) \
do { \
@@ -44,7 +44,7 @@ char *tflag = NULL;
time_t oflag = 0;
/*
-** Set `str' to a human-readable form of `num' with always a width of 7 (+ 1
+** Set 'str' to a human-readable form of 'num' with always a width of 7 (+ 1
** the '\0' terminator). Buffer overflow is ensured not to happen due to the
** max size of a double.
*/
@@ -67,7 +67,7 @@ humanize(char *str, double val)
}
/*
-** Returns the maximal double of values between `beg' and `end'.
+** Returns the maximal double of values between 'beg' and 'end'.
*/
double
maxdv(double *beg, double *end)
@@ -83,7 +83,7 @@ maxdv(double *beg, double *end)
}
/*
-** If not null, print the title `str' centered on width.
+** If not null, print the title 'str' centered on width.
*/
void
title(char *str, int width)
@@ -95,7 +95,7 @@ title(char *str, int width)
/*
** Print vertical axis with humanized number from time to time, with occurences
-** determined after the position on the vertical axis from the bottom `pos'.
+** determined after the position on the vertical axis from the bottom 'pos'.
*/
void
vaxis(double val, int pos)
@@ -111,7 +111,7 @@ vaxis(double val, int pos)
}
/*
-** Print horizontal axis for up to `col' values along with dates if reading time
+** Print horizontal axis for up to 'col' values along with dates if reading time
** series.
*/
void
@@ -152,8 +152,8 @@ line(double *beg, double *end, double top, double bot)
}
/*
-** Plot values between `beg' and `end' in a plot of height `height'.
-** If `str' is not NULL, it is set as a title above the graph.
+** Plot values between 'beg' and 'end' in a plot of height 'height'.
+** If 'str' is not NULL, it is set as a title above the graph.
*/
void
plot(double *beg, double *end, int height, char *str, time_t start)
@@ -181,8 +181,8 @@ plot(double *beg, double *end, int height, char *str, time_t start)
}
/*
-** Read a simple format with one double per line and save the last `MAX_WIDTH'
-** values into `buf' which must be at least MAX_VAL wide and return a pointer
+** Read a simple format with one double per line and save the last 'MAX_WIDTH'
+** values into 'buf' which must be at least MAX_VAL wide and return a pointer
** to the last element or NULL if the input contains error.
*/
double *
@@ -203,8 +203,8 @@ read_simple(double buf[MAX_VAL])
/*
** Read a format with blank separated time_t-double pairs, one per line and save
-** the last `MAX_WIDTH' values into `tbuf' and `vbuf' which must both be at
-** least MAX_VAL wide and return a pointer to the last element of `vbuf' or
+** the last 'MAX_WIDTH' values into 'tbuf' and 'vbuf' which must both be at
+** least MAX_VAL wide and return a pointer to the last element of 'vbuf' or
** NULL if the input contains error.
*/
time_t *
@@ -229,8 +229,8 @@ read_time_series(double *vbuf, time_t *tbuf)
}
/*
-** Walk from `tbeg' and `tend' and add offset in `tbuf' every time there is no
-** value in `step' amount of time, by setting a value to -1.
+** Walk from 'tbeg' and 'tend' and add offset in 'tbuf' every time there is no
+** value in 'step' amount of time, by setting a value to -1.
*/
double *
skip_gaps(time_t *tbeg, time_t *tend, double *vbuf, time_t step)
@@ -246,7 +246,7 @@ skip_gaps(time_t *tbeg, time_t *tend, double *vbuf, time_t step)
toff += *tp % step;
toff = *tbeg + toff / (tend - tbeg) + step / 2;
- /* Fill `vbuf' with gap added at each time gap using vrbuf as
+ /* Fill 'vbuf' with gap added at each time gap using vrbuf as
** intermediate ring buffer. */
len = LEN(vrbuf);
for (p = pos = 0, tp = tbeg, vp = vbuf; tp < tend; p++, vp++, tp++) {