add a byte stream: pxl8_stream

src/pxl8_io.h

@@ -5,6 +5,80 @@
 
 #include "pxl8_types.h"
 
+typedef struct {
+    const u8* bytes;
+    u32 offset;
+    u32 size;
+} pxl8_stream;
+
+static inline pxl8_stream pxl8_stream_create(const u8* bytes, u32 size) {
+    return (pxl8_stream){
+        .bytes = bytes,
+        .offset = 0,
+        .size = size
+    };
+}
+
+static inline bool pxl8_stream_can_read(const pxl8_stream* stream, u32 count) {
+    return stream->offset + count <= stream->size;
+}
+
+static inline void pxl8_stream_seek(pxl8_stream* stream, u32 offset) {
+    stream->offset = offset;
+}
+
+static inline u32 pxl8_stream_position(const pxl8_stream* stream) {
+    return stream->offset;
+}
+
+static inline u8 pxl8_read_u8(pxl8_stream* stream) {
+    return stream->bytes[stream->offset++];
+}
+
+static inline u16 pxl8_read_u16(pxl8_stream* stream) {
+    u16 val = (u16)stream->bytes[stream->offset] | ((u16)stream->bytes[stream->offset + 1] << 8);
+    stream->offset += 2;
+    return val;
+}
+
+static inline u32 pxl8_read_u32(pxl8_stream* stream) {
+    u32 val = (u32)stream->bytes[stream->offset] |
+              ((u32)stream->bytes[stream->offset + 1] << 8) |
+              ((u32)stream->bytes[stream->offset + 2] << 16) |
+              ((u32)stream->bytes[stream->offset + 3] << 24);
+    stream->offset += 4;
+    return val;
+}
+
+static inline i16 pxl8_read_i16(pxl8_stream* stream) {
+    return (i16)pxl8_read_u16(stream);
+}
+
+static inline i32 pxl8_read_i32(pxl8_stream* stream) {
+    return (i32)pxl8_read_u32(stream);
+}
+
+static inline f32 pxl8_read_f32(pxl8_stream* stream) {
+    u32 val = pxl8_read_u32(stream);
+    return *(f32*)&val;
+}
+
+static inline void pxl8_read_bytes(pxl8_stream* stream, void* dest, u32 count) {
+    for (u32 i = 0; i < count; i++) {
+        ((u8*)dest)[i] = stream->bytes[stream->offset++];
+    }
+}
+
+static inline void pxl8_skip_bytes(pxl8_stream* stream, u32 count) {
+    stream->offset += count;
+}
+
+static inline const u8* pxl8_read_ptr(pxl8_stream* stream, u32 count) {
+    const u8* ptr = &stream->bytes[stream->offset];
+    stream->offset += count;
+    return ptr;
+}
+
 #ifdef __cplusplus
 extern "C" {
 #endif