C Backend

Generate C source code from dew expressions.

Enable

dew-scalar = { version = "0.1", features = ["c"] }
dew-linalg = { version = "0.1", features = ["c"] }

dew-scalar

Generate Expression

use dew_core::Expr;
use dew_scalar::c::emit_c;

let expr = Expr::parse("sin(x) + cos(y)").unwrap();
let c = emit_c(expr.ast()).unwrap();

println!("{}", c.code);
// Output: (sinf(x) + cosf(y))

Generate Function

use dew_scalar::c::emit_c_fn;

let expr = Expr::parse("x * x + y * y").unwrap();
let c = emit_c_fn("distance_squared", expr.ast(), &["x", "y"]).unwrap();

println!("{}", c);
// Output:
// float distance_squared(float x, float y) {
//     return ((x * x) + (y * y));
// }

Function Mapping

dew	C
sin(x)	sinf(x)
cos(x)	cosf(x)
sqrt(x)	sqrtf(x)
abs(x)	fabsf(x)
floor(x)	floorf(x)
x ^ y	powf(x, y)
x % y	fmodf(x, y)
min(a, b)	fminf(a, b)
max(a, b)	fmaxf(a, b)
pi()	M_PI
e()	M_E

Limitations

The C backend generates code that assumes external type and function definitions.

Required Type Definitions (User-Provided)

// Vectors (structs with component fields)
typedef struct { float x, y; } vec2;
typedef struct { float x, y, z; } vec3;
typedef struct { float x, y, z, w; } vec4;

// Matrices (column-major)
typedef struct { vec2 cols[2]; } mat2;
typedef struct { vec3 cols[3]; } mat3;
typedef struct { vec4 cols[4]; } mat4;

// Complex numbers
typedef struct { float re, im; } complex_t;

// Quaternions
typedef struct { float x, y, z, w; } quat_t;

Required Function Definitions (User-Provided)

// Vector operations
vec2 vec2_add(vec2 a, vec2 b);
float vec2_dot(vec2 a, vec2 b);
vec2 vec2_scale(vec2 v, float s);
vec2 vec2_normalize(vec2 v);
float vec2_length(vec2 v);

// Matrix operations
mat2 mat2_mul(mat2 a, mat2 b);
vec2 mat2_mul_vec2(mat2 m, vec2 v);

// Complex operations
complex_t complex_mul(complex_t a, complex_t b);
complex_t complex_conj(complex_t z);

// Quaternion operations
quat_t quat_mul(quat_t a, quat_t b);
quat_t quat_slerp(quat_t a, quat_t b, float t);

Standard C Functions Used

From <math.h>:

• sinf, cosf, tanf, asinf, acosf, atanf, atan2f
• expf, logf, log2f, log10f, powf, sqrtf
• fabsf, floorf, ceilf, roundf, truncf, fmodf
• fminf, fmaxf, copysignf

Use Cases

• Embedded systems: Generate C for microcontrollers
• Game engines: Integrate with existing C/C++ math libraries (cglm, HandmadeMath)
• FFI: Create C code callable from other languages
• Legacy integration: Embed in existing C codebases